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PICList Thread
'PIC-related brainteaser'
1996\09\18@092723 by Clyde Smith-Stubbs

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Here's a PIC-related brainteaser, just to add fuel to the fire;

A device contains only two off-the-shelf components, is powered from
an external constant-voltage supply, and has an input-output transfer
function that looks like the first 180 degrees of a sine wave. The
output units are volts.

What are the input units, and how many digits are required to express
the full input range?

Bonus question - why is this PIC-related?

--
Clyde Smith-Stubbs       | HI-TECH Software,       | Voice: +61 7 3354 2411
spam_OUTclydeTakeThisOuTspamhitech.com.au      | P.O. Box 103, Alderley, | Fax:   +61 7 3354 2422
http://www.hitech.com.au | QLD, 4051, AUSTRALIA.   |
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For info on the World's best C cross compilers for embedded systems, point
your WWW browser at http://www.hitech.com.au, or email .....infoKILLspamspam@spam@hitech.com.au

'PIC-related brainteaser update'
1996\09\18@195934 by Clyde Smith-Stubbs

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Well, so far one person (Kalle Pihlajasaari <kallespamKILLspamdevice.data.co.za>)
has solved this problem - and in a disgustingly short time, too! And he
got the bonus question right!

Andy (not the other one) gave up :%( - he blamed it on lack of sleep.

I'll add some hints;

both components are carbon-based, as is the input source.
f(0) == f(max) == 0.

And to the stuffed-shirts; remember Dr. Dobbs Journal of Computer
Calisthenics and Orthodontia? Maybe we should rename this list
Dr. PIC's Microcontrollers and Neurosurgery.

Cheers.

{Quote hidden}

--
Clyde Smith-Stubbs       | HI-TECH Software,       | Voice: +61 7 3354 2411
.....clydeKILLspamspam.....hitech.com.au      | P.O. Box 103, Alderley, | Fax:   +61 7 3354 2422
http://www.hitech.com.au | QLD, 4051, AUSTRALIA.   |
---------------------------------------------------------------------------
For info on the World's best C cross compilers for embedded systems, point
your WWW browser at http://www.hitech.com.au, or email EraseMEinfospam_OUTspamTakeThisOuThitech.com.au

1996\09\20@094751 by Andrew David

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part 0 572 bytes

I don't suppose you'd tell me the answer if I asked nicely? ;-)

The question on Fast Forwards page (under "what we want") has a
simple answer. Squircle.

regards,

- Andy.


*************************************************************
Andrew David               Senior Project Engineer - Software

Ultronics Division         Andyspamspam_OUTUltronics.co.uk
Ultra Hydraulics Ltd.
Anson Business Park
Cheltenham Road East
Staverton
Glos. GL2 9QN

Tel.: (01452) 858376 (Direct)  Ultronics Fax.: (01452) 858377
*************************************************************

1996\09\20@112704 by Clyde Smith-Stubbs

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Andrew David <@spam@AndyKILLspamspamULTRONICS.CO.UK> wrote:

> Clyde,
>
> I don't suppose you'd tell me the answer if I asked nicely? ;-)

Well, since only Kalle has solved it so far, I will enlighten the
rest of you.

The input units are degrees rotation, and the number of digits
required is two - thumb and finger. (Or if you use
a slider pot, it's mm and one).

The two components are a pot and a resistor. The exact circuit
is left as an exercise for the reader :-)

Oh, the bonus question; the answer is nothing - I lied about
it being PIC related. Sorry :-)

--
Clyde Smith-Stubbs       | HI-TECH Software,       | Voice: +61 7 3354 2411
KILLspamclydeKILLspamspamhitech.com.au      | P.O. Box 103, Alderley, | Fax:   +61 7 3354 2422
http://www.hitech.com.au | QLD, 4051, AUSTRALIA.   |
---------------------------------------------------------------------------
For info on the World's best C cross compilers for embedded systems, point
your WWW browser at http://www.hitech.com.au, or email RemoveMEinfoTakeThisOuTspamhitech.com.au


'PIC UART/BRG brain damage (was Manual humor)'
1997\01\15@175834 by Eric Smith
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face
I wrote:
> There certainly isn't much humor to be found in Microchip manuals.  Sigh.

To which Todd Peterson <spamBeGoneelabspamBeGonespamNETINS.NET> replied:
> Sure there is.  All the stuff about BRGH=1 is a joke.

Yes.  Pretty pathetic, though.  It's not like UARTs and BRGs are rocket
science.  All the other vendors seem to be able to make them work correctly
without too much trouble.  But Microchip can't make them work even after
multiple revisions of the silicon :-(

1997\01\16@031033 by Wolfram Liebchen

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At 23:55 15.01.97 -0000, you wrote:
>Yes.  Pretty pathetic, though.  It's not like UARTs and BRGs are rocket
>science.  All the other vendors seem to be able to make them work correctly
>without too much trouble.  But Microchip can't make them work even after
>multiple revisions of the silicon :-(
>
I think, there are also other manufacturers, who have problems with
their UARTs.

 - The first version of 16550 should not have been used with its FIFO.

 - The SCC-2692 datasheets tells something about lost characters under
   certain circumstances (reads horrible, but seems to work in praxi).

So there might exist other UARTs with problem, but you simply don't know
it and therefor your happy.
It's good, that Microchip reports the bugs.

regards

Wolfram


+-----------------------------------------------------+
| Wolfram Liebchen                                    |
| Forschungsinstitut fŸr Optik, TŸbingen, Deutschland |
| TakeThisOuTliebchenEraseMEspamspam_OUTffo.fgan.de                         |
+-----------------------------------------------------+


'PIC_k You Brains'
1998\10\08@235507 by Dr. Ed Edmondson, Jr. Ph.D.
picon face
I am really glad to see that all you picsters are so easily amused :-)).
Technical people with a good sense of humor are hard to find.

What I need to do is just PIC your brains a little.  I have all the hardware,
software and books to learn what to do with these PIC devices.  What I need is
a little bit of direction.  I am wanting to build a model rocket launcher for
a friend who has an asthmatic son.  I have seen some simple designs but tend
to lean towards the flair for bells and whistles.  So what I will have a very
I/O intensive little PIC.

I want to use 10 LED's for the launch sequence (10, 9, 8, 7, ....2, 1, L).
These LED's will count down in sequence with the last LED "L" flashing at
about 1-2 Hz at launch.  I want to use a piezo alarm to sound a launch warning
for the last 4 counts (LED's 4, 3, 2, 1, L).  Then there would be a dual
RED/GREEN LED for the Fuze continuity check and a button for this test (maybe
it could be automated).  Then we have a flashing (1-2 Hz) red LED to indicate
the countdown has been halted due to emergency and a button to activate this
feature.  There is also a flashing yellow LED (1-2 Hz) to indicate a temporary
hold on the countdown sequence and the button to hold and restart the
countdown.  Two buttons for on and off and a green LED to indicate power "ON."

I also want a master reset button (Must be held in for 5 -10 seconds) to reset
the whole system to a known state and disable the launch circuit.  I am
planning on using a key switch for the master interlock on the launch circuit.
This and maybe using a SSR to isolate the launch and Fuzing circuit will
enhance the safety issue.  I want the unit to also go "To Sleep" after 5 or 10
minutes of inactivity.  Pressing any key would reawaken the system in the
state it was in prior to "Sleep."

Finally it would be great to have some form of battery condition indicators.
Maybe a small LCD voltmeter to measure battery voltage or current.  Maybe a
battery gas gauge like Benchmarq sells for high priced power tools.  Maybe use
the display for a clock too?  Want to be able to use alkaline or rechargeable
batteries to power the thing.  It would be great if it could be charged from
an auto cigarette lighter!!

What I need is suggestions on  what PIC  might really fit the bill here.
There is a lot of I/O, a watch dog timer, maybe an A/D, should be able to
drive LED's, an SSR, a piezo audio indicator, determine battery condition and
charge state.  And much more.

With all these bells and whistles this asthmatic young teen could have the
ABSOLUTE neatest model rocket launcher at the contests.  This is his only form
of recreation due to his exacerbated condition.

What I will get out of this journey, in addition to his smiles, is the
knowledge earned from getting this thing designed and built.  I have MPLAB on
a Compaq Presario 1610 and a PIC Start Plus Programmer.  I have all the PIC
books written by anyone I could find.  I have a free source for the PIC chips.
What I need is direction and suggestions along the way.

Want to help??  The only real concern is SAFETY to prevent an accidental
launch which might cause an injury.  This can be avoided with some old
fashioned design criteria and common sense.  I have until December 24th to get
this done.  Any direction and comments would be greatly appreciated by the
recipient and myself.

Ed

1998\10\09@010249 by James Cameron

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Since you are design phase, Ed, I'd suggest a few other changes ...

Add a wide angle passive infrared motion detector to the launch pad, so
that it refuses to commence a countdown if people are close to it.
Maybe even abort a countdown.

Since some of the system has to do with safety, I would avoid placing
those features in code in the PIC, but rather as hardware interlocks
outside the code.  See the "Risks Digest" for the past ten years for
good reasons why.  ;-)

--
James Cameron                                    (RemoveMEcameronspamTakeThisOuTstl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800

1998\10\09@010606 by paulb

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face
Dr. Ed Edmondson, Jr. Ph.D. wrote:

> I want to use 10 LED's for the launch sequence (10, 9, 8, 7, ....2, 1,
> L).

 No way!  You want two large, bright 7-segment displays.  Of course,
these can also display voltage etc., though a number of small ones as
well (note my previous comments on multiplexing) would be great.  Have
you not seen all the neat patterns you can play on 7-seg. displays?

 Need a sun-hood.

> What I need is suggestions on  what PIC  might really fit the bill
> here.

 Prototype on 16C84, then on 16C71(x)/JW if you need ADC, burn on
16C71.  If you use interfacing right, that'll do.

> I have a free source for the PIC chips.

 Oh weellll!
--
 Cheers,
       Paul B.

1998\10\09@042630 by ruben

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Hello Ed
.....
> This and maybe using a SSR to isolate the launch and Fuzing circuit will
> enhance the safety issue.
....
> Want to help??  The only real concern is SAFETY to prevent an accidental
> launch which might cause an injury.  This can be avoided with some old
> fashioned design criteria and common sense.  I have until December 24th to get
> this done.  Any direction and comments would be greatly appreciated by the
> recipient and myself.
>
> Ed

About safety.

Use two separate channels (2 processors with 2 different programs preferably
by two different programmers), both handling all safety parameters in parallel.
Both channels have one 2 pole positive action (safety) relays where one pole is
used for output in series with one of the other channels relay. The other pole i
s
used for crosschecking the relay outputs between the two channels (both
channel are checking the other channels relay). The processors should have a
pulsed output to activate the safety relays, through for example a transformer
(so that a static output can't activate the relay).

The two processors should have some sort of communication between them in
order to be able to check each other (check that the programs are working and
that they have the same result on safety related conclusions).

Use two separate sensors, one for each channel, for every safety related input.
Design the input stage so the processors can check short circuited active
inputs (one output can turn off the input stage, check that the processor input
for the safety function can be set to inactive state by the output when the safe
ty
sensor is activated). To control the actual input - make it dynamic (so that the
program can check that it at some point is off and not shorted to the active
state). For example for a push button initiate the action when the button is fir
st
pressed and then released. Or, for static inputs have a maximum time
difference between the two sensors (two channels) for them to be able to
activate an event and set it as a condition that the sensor must be deactivated
at
power up (so a short is detected).

All safety related electronics should be designed so that a failure in one
component doesn't lead to a potentially dangerous state if it can't be discovere
d
by the processors. Test that no potentially dangerous state can be initiated by
a
shortcircuit between any two pins/legs on a any circuit or terminal. (If the sho
rt
circuit isn't detected restart the test with the pins shorted, do this up to thr
ee
levels if another short circuit is undetected). A processor which, when reading
an output pin reads the actual pin and not the output latch is good here.

In the program flow: Both channels continuously checks each other through the
communication lines. If the response is unexpected put the channel that found
the error in an interlocked state which can't be aborted and turn the safety rel
ay
off. Continously check the other channel's relay - if it doesn't match this
channel - go to interlock state.

Safety related RAM registers should continously be checked that they can be
changed and that a write to some other RAM register doesn't affect this
register. At power up the integrity of the program should be checked by some
sort of checksum test of the EPROM (can't be done in a PIC, use a SCENIX).
Also, all instructions used by safety related functions should be checked at
power up.

One channel could handle all the whistels and bells plus the safety and the othe
r
channel could handle just the safety.

This may sound a bit overworked but it is how a human safety device of
category 4 is done for industrial purposes (light barrier, light courtains,
emergency stops etc.)



--------------------------------------------
Ruben Jvnsson
AB Liros Elektronik
Box 9124, 200 39 Malmv, Sweden
TEL INT +4640142078
FAX INT +4640947388
rubenEraseMEspam.....2.sbbs.se
--------------------------------------------

'PICk your brain rocket launcher'
1998\10\09@100021 by John P. Leonard

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OK Ed, you've teased us!  Now what are all the bells and whistles you want
to add that won't make it simple???

John
______________________________________________________________________________

John Leonard, analytica inst. tech.                        Electron Hacker
College of Science & Engineering                           Bit Banger
Saginaw Valley State University                            Fretless Bassist
University Center, MI USA  48710                           Dad
_____________________________________________________________________________

'PIC_k You Brains'
1998\10\09@124914 by Morgan Olsson

picon face
Ruben Joensson wrote:

-big snip of a very thorough safety strategy-

>At power up the integrity of the program should be checked by some
>sort of checksum test of the EPROM (can't be done in a PIC, use a SCENIX).

I have not used a PIC17, but I believe we can use the table read to read
all program memory?

For PIC16, i have been thinking: as we have two processors, they might be
able to set each other in serial programming mode and read each other by
use of little external hardware... No, much better use PIC17 or other
processor...

I want to add:

The program memory check sould be run now and then, as the eprom slowly
degrades by age, and is probably more possible that the first erroneous
reading will take place during normal execution (!), as the EPROM is
sensitive to both voltage and temperature (and supply noise too), which
will vary during execution.

To achieve a margin, we better test the eprom at slightly worse conditions
than when runnig the safety routines.  Therefor, the testing should be run
at bot slightly lower, and slightly higher supply voltage trying to stress
up errors of "0" and "1" bits respectively.

This can easily be achieved, as one pin can via a resistor be connected to
the voltage regulator feedback loop (i.e on a LM317-regulator), and use all
three states (High/Tristate/Low).
Take care in design so there is not too fast change or overshoot.

Timing proposal:

RESET:
Initialize to output "safety violated" state
Set lower voltage
wait to stabilize voltage (sleep, and wake of timer interrupt?)
-Check system-
Set normal voltage         ;Two-step to minimize overshoot
wait to stabilize voltage       ;
Set higher voltage              ;
wait to stabilize voltage       ;
-Check system-
MAIN:
Set normal voltage
wait to stabilize voltage
[Run a safety pass]
Set lower voltage
wait to stabilize voltage
-Check system-
Set normal voltage
wait to stabilize voltage
[Run a safety pass]
Set higher voltage
wait to stabilize voltage
-Check system-
GOTO MAIN

Also, all theese "-Check system-" routines above should check EEPROM to a
checksum, and also test as much as possible of the rest of the chip (all
that possibly can be tested-restored, or checksum compared etc), Like XOR
FF twice to every RAM and see if it still reads the same.  Check if timer
or other things give interrupt correctly, etc.
Also run a small routine tht use all CPU hardware and see that it always
give the right result.  Best also to run for different input values.

I wonder what do Mchip use to test the chips;  They should be able to tell
a complete chip test scheme for every processor :)

Best also to test external cirquitry during over/under voltage.

The test routine can of course be split to do part of the test each time.
Also the safety routines might sometimes temporarily be too busy doing
something, but when finished, continue with the system check. (safety: max
time set by watchdog)

I think I better stop now...
I was going to suggest a small simple RF-sweep oscillator that the PIC
enables to inject noise on supply during test... Oops.. I did   ;)

I have never used anything except watchdog and brown-out yet...

BTW, a better Watchdog might be good, like one that needs toggling within
defined time high and low *windows*.
So, also talking too much with the watchdog causes reset.
I believe Maxim or LTC make them.
Or wire your own.
Or, maybe cheapest, use a 8-pin PIC !

Regards
/Morgan
/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, SWEDEN \
\  EraseMEmrtspaminame.com     ph +46(0)414 70741     fax +46(0)414 70331 /

1998\10\09@130351 by Justin Crooks

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face
Use a PIC16C74.  Lots of I/O pins, A/D no problem.  My battery check ckt is
nice and simple.  For 9V batteries, I use a 2N2222A transistor.  Connect a
digital I/O pin to the base via a 100K resistor.  this is your on/off so
the ckt does not draw current when not needed.  Connect a 2.2k resistor b/w
emitter and ground.  A 9.1K goes b/w collector and Vbat+.  The analog
voltage at the emitter (with a high applied to the base) will convert to
your battery voltage in tenths of volts if your Vref is +5V.

I recommend the abort key be instant, without delay (safety).  with a
PIC16C74, each LED could have its own I/O pin, with pins for future
enhancements readily available.

----------
> From: Dr. Ed Edmondson, Jr. Ph.D. <RemoveMEDreaejrphdEraseMEspamEraseMEAOL.COM>
> To: RemoveMEPICLISTspam_OUTspamKILLspamMITVMA.MIT.EDU
> Subject: PIC_k You Brains
> Date: Thursday, October 08, 1998 9:52 PM
>
> I am really glad to see that all you picsters are so easily amused :-)).
> Technical people with a good sense of humor are hard to find.
>
> What I need to do is just PIC your brains a little.  I have all the
hardware,
> software and books to learn what to do with these PIC devices.  What I
need is
> a little bit of direction.  I am wanting to build a model rocket launcher
for
> a friend who has an asthmatic son.  I have seen some simple designs but
tend
> to lean towards the flair for bells and whistles.  So what I will have a
very
> I/O intensive little PIC.
>
> I want to use 10 LED's for the launch sequence (10, 9, 8, 7, ....2, 1,
L).
> These LED's will count down in sequence with the last LED "L" flashing at
> about 1-2 Hz at launch.  I want to use a piezo alarm to sound a launch
warning
> for the last 4 counts (LED's 4, 3, 2, 1, L).  Then there would be a dual
> RED/GREEN LED for the Fuze continuity check and a button for this test
(maybe
> it could be automated).  Then we have a flashing (1-2 Hz) red LED to
indicate
> the countdown has been halted due to emergency and a button to activate
this
> feature.  There is also a flashing yellow LED (1-2 Hz) to indicate a
temporary
> hold on the countdown sequence and the button to hold and restart the
> countdown.  Two buttons for on and off and a green LED to indicate power
"ON."
>
> I also want a master reset button (Must be held in for 5 -10 seconds) to
reset
> the whole system to a known state and disable the launch circuit.  I am
> planning on using a key switch for the master interlock on the launch
circuit.
> This and maybe using a SSR to isolate the launch and Fuzing circuit will
> enhance the safety issue.  I want the unit to also go "To Sleep" after 5
or 10
> minutes of inactivity.  Pressing any key would reawaken the system in the
> state it was in prior to "Sleep."
>
> Finally it would be great to have some form of battery condition
indicators.
> Maybe a small LCD voltmeter to measure battery voltage or current.  Maybe
a
> battery gas gauge like Benchmarq sells for high priced power tools.
Maybe use
> the display for a clock too?  Want to be able to use alkaline or
rechargeable
> batteries to power the thing.  It would be great if it could be charged
from
> an auto cigarette lighter!!
>
> What I need is suggestions on  what PIC  might really fit the bill here.
> There is a lot of I/O, a watch dog timer, maybe an A/D, should be able to
> drive LED's, an SSR, a piezo audio indicator, determine battery condition
and
> charge state.  And much more.
>
> With all these bells and whistles this asthmatic young teen could have
the
> ABSOLUTE neatest model rocket launcher at the contests.  This is his only
form
> of recreation due to his exacerbated condition.
>
> What I will get out of this journey, in addition to his smiles, is the
> knowledge earned from getting this thing designed and built.  I have
MPLAB on
> a Compaq Presario 1610 and a PIC Start Plus Programmer.  I have all the
PIC
> books written by anyone I could find.  I have a free source for the PIC
chips.
> What I need is direction and suggestions along the way.
>
> Want to help??  The only real concern is SAFETY to prevent an accidental
> launch which might cause an injury.  This can be avoided with some old
> fashioned design criteria and common sense.  I have until December 24th
to get
> this done.  Any direction and comments would be greatly appreciated by
the
> recipient and myself.
>
> Ed

1998\10\09@132652 by John Payson

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part 0 919 bytes
First of all, I think that rather than spending oodles of effort to
make the PIC foolproof it's probably better to simply have hardware
outside the PIC to prevent launch in unsafe conditions.  The simplest
way to do this would be to have a "deadman" switch for the launch
current in series with the igniter: for the countdown to proceed the
switch must be held pressed; if the switch isn't pressed the PIC is
completely unable to launch the rocket no matter how it malfunctions.

Since nobody should be pressing the switch any time the launch pad is
not safe, nothing in the operation of the PIC should be able to pose
any hazard.  If the PIC malfunctions it may cause the rocket to launch
sooner after the contact closure than it would otherwise, but if any
sort of reasonable launchpad safety precautions are taken (e.g. don't
push the button while someone's at the launchpad) that shouldn't be a
problem.

1998\10\09@185012 by Mark Willis

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face
A safety tip I'll add;  Shorting the firing leads except when launch
is imminent isn't a bad idea.

 Also: You can use a pair of big 3PDT switches, wired with an
appropriate flashlight bulb (or buzzer) and a resistor, so that in safe
mode, the input wires are across the bulb/buzzer, and the output wires
are connected together, through that resistor, to reduce any chance of
static or induced RF currents;  In "Fire" mode, it's just a
straight-through connection from the controls to the launch pad.

 Put one or even two of these in series (Set one 10 feet away from the
control station, one 10 feet from the rocket launchpad) is an safety
trick that I like (The 1k resistor can be a short, I've heard arguments
re: RF transmissions as to which is safer, but not kept up on that;
Twisted pair wire isn't a bad idea if you do use a short.  Probably
pretty safe either way, so long as your wires are kept close together!)

 As you walk down range, with safety key in your hand, you flip the one
& then the other safety to "Safe" and then continue.  Hard to get an
accidental launch this way!  Then as you walk back to the launch
console, you flip each to "Fire" as you pass.  AGAIN, do not flip the
circuit to "Fire" if the light bulb there is lit or the buzzer's
buzzing, as that's a really bad sign <G>

 I sketched this for a guy who had a blasting permit and had some idiot
handle his blasting box while he was putting in 30 pounds or so of ANFO
explosives to blow a big stump; His has LOUD buzzers so he knows when to
panic <G>  It's not a bad design for model rocketry; maybe a little
over-paranoid to use two, but one of these set to "Safe", 10 feet away
from a Multi-F engine cluster would make ME for one a lot less paranoid
about sticking my face in close to examine the ni-chrome ignitor
connections!  Safety console keys can be faked, I value my eyes.  (I
always used a pre-soldered rig with a paper clip loop etc. for even
3-C-engine clusters, less mis-fires that way.  Just 2 connections &
you're set.)

 Mark, RemoveMEmwillisTakeThisOuTspamspamnwlink.com

Dr. Ed Edmondson, Jr. Ph.D. wrote:
>
> I am really glad to see that all you picsters are so easily amused :-)).
> Technical people with a good sense of humor are hard to find.
>
> <snipped>

1998\10\09@195227 by James Cameron

flavicon
face
Mark Willis wrote:
> A safety tip I'll add;  Shorting the firing leads except when launch
> is imminent isn't a bad idea.

Assuming of course that you have used twisted pair all the way from the
point of short to the fuse, and you are certain there are no large
sources of EMF around.

I'd heard that explosives experts do _not_ short the cable at the end
they are rolling out, because that creates a loop circuit in which any
radio energy will just _have_ the be consumed by the detonator.

Just rumour.  I'm not qualified to advise on this.

--
James Cameron                                    (EraseMEcameronspamspamspamBeGonestl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800

1998\10\09@201758 by g.daniel.invent.design

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Morgan Olsson wrote:
>
> Ruben Joensson wrote:
>
> -big snip of a very thorough safety strategy-
>
> >At power up the integrity of the program should be checked by some
> >sort of checksum test of the EPROM (can't be done in a PIC, use a SCENIX).
>
Morgan,
PIC 16C715 has integral checksum fail reset built in to prog memory.
(adds that litle extra time to coding the down loader)
regards,
Graham Daniel,
Electronic Product Enhancements.

'PIC_k You Brains; RF PIC_k-up'
1998\10\10@222655 by paulb

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James Cameron wrote:

> I'd heard that explosives experts do _not_ short the cable at the end
> they are rolling out, because that creates a loop circuit in which any
> radio energy will just _have_ to be consumed by the detonator.

 It would be most sensible to terminate it with a resistor about 100
ohms.  This is a reasonable approximation to the characteristic
impedance of the cable, and should prevent resonance, which is what is
being discussed.  Also, it should be much greater than the fuse
resistance so that most of any power received would be dissipated in the
terminator and only a very small proportion in the fuse.

 It depends on the length of wire vs. the wavelength of the RF in
question.  A quarter wave of cable with fuse (shorted in effect) at one
end and open at the other will resonate with maximum current at the
fuse end (bang!).

 A half wave with fuse at one end and shorted at the other can also
resonate with the same effect.  Any other length however will not
resonate, and a *much* greater field would be required to induce
appreciable current.

 Twisted or not, a close-spaced parallel cable represents a
transmission line whose function is *not* to pick up RF.  It will only
do so if the wires are appreciably separated at places subject to an
RF field (you'd be pretty dumb to go blasting/ rocket launching within
a mile of the local AM radio station, or at the same level as the FM one
for example!).  Good practice dicatates keeping the wires together *all*
the way.

 Of course all this is exclusively for the benefit of the *non*- radio
amateurs on the list ;-)
--
 Cheers,
       Paul B.

1998\10\10@222709 by Nicholas Irias

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I think any recommendation regarding missile safety is incomplete if we dont
also recommend dual launch switches, located at least 6 feet apart, that
must be pressed simultaneously.  That way, a single crazed rocketeer cant
launch your rocket.

'John Leonard's PICk your brain rocket launcher'
1998\10\11@013425 by Dr. Ed Edmondson, Jr. Ph.D.

picon face
John Leonard:

Thanks for the REALLY constructive input you provided.  I can see as a father
(DAD) you might need a little input from other experienced fathers like
myself!

This kind of help is why so many children grow up like they do today.  They,
like so many others, ask for REAL help or constructive comments and yours is
the most common response received.

You may very well find this amusing but people trying to help others as I was
attempting to do, DON'T.  For the most part the feedback from nearly all  of
the picsters has been helpful and constructive, sans yours.  Just for grins
:-)) you take a large soda straw and you breath through it for a complete day
(if you are able) and you will see how it feels to be a chronic asthmatic.
Take away the ability to run, play any kind of sports, of even walk up a
flight of stairs without a problem and see how much you like it.  This is one
of the VERY FEW things this young man can do.  I was only trying to give him
an alternative to the junk that is currently available, not trying to impress
you or any one else with what I know or don't know.

If indeed this is the kind of help you provide on a constant basis to the rest
of the people on this list, maybe you would better spend your time taking
remedial parenting classes.

As for the rest of you picsters,  thank you for your honest concerns, comments
and REAL help.  I know Ray will be appreciative of your contributions.  I will
continue to value any input put forth by the sincere contributors among you as
I still have a long way to go.  I too hope to be able one day to be a
contributor to those many seeking REAL help here.

Sincerely,
Ed

'PIC_k You Brains'
1998\10\11@015119 by Dr. Ed Edmondson, Jr. Ph.D.

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Ruben:

Thank you very much for the contribution on the safety mechanism for fuzing
and accident prevention.  Since these PIC's are so very inexpensive the
thoughts you suggested are really not far out of the realm of consideration.
I do see where it might take a lot of program development.  Would you use
something like I2C to communicate between the two processors?  Or is there a
simpler or better method for two PIC's to cross communicate with one another?

Ed

1998\10\11@020401 by Dr. Ed Edmondson, Jr. Ph.D.

picon face
Paul,

If you use LED displays why not just use a backlit LCD display.  The back
light for the late evenings?  The LCD would remove the need for a hood over
the display and the washout effect of the sun light.  The display could even
be a smart module available from Dontronics or Wirz Electronics.

Probably not as impressive as a lot of LED's but certainly overcomes the
problem of wash out.  If I used LED's I was going to use the newer low current
high output types.  I was going to have them in a fluted polycarbonate clear
lens assembly extending from the front panel about 0.250."

The display idea might be more manageable because of the ability to multiplex
the data and signal lines with the control switched and buttons.  I was going
to use a keypad and overlay for these functions.  It may be more coding and
software since you might want to toggle "ON - OFF" with one button.  Have
another as a "Hold - Resume" count switch?

Comments??

Ed

1998\10\11@020816 by Dr. Ed Edmondson, Jr. Ph.D.

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James,

Where do I find this RISK document you have referenced?

Ed

1998\10\11@022453 by Dr. Ed Edmondson, Jr. Ph.D.

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Morgan,

Your input is really great.  What do you think about the saga of discrete
LED's Vs LED or LCD displays?  I was thinking LED's for effect but there might
be a washout problem with the sunlight.

What about using opto isolators to isolate the firing link.  I built a very
simple launcher for my son about two years ago.  It used an FET and large
capacitor to ignite the fuze.  At the end of the countdown the counter turned
on the FET and dumped 6VDC and the charge from the capacitor into the fuze.
The wire shipped with the ESTES (the rocket kit, engine and fuze manufacturer)
is nothing more than gray zip cord (2 conductors) like they use to wire CHEAP
car stereo speakers with (approximately 22 gauge).  They supply 25 feet with
small clips on the ends.  The fuzes are extremely low resistance wire with an
ignitor substance deposited on the wire.  The fuze is only about 3" long.  The
primary fuze failure mode is not getting enough of a current pulse to the
fuse, hence the 2,000 plus uF capacitor hanging out there.

I am sure this will bring out a few other questions.  How about a clever way
to detect fuze continuity without igniting the fuze?  Or maybe, using a
circuit to charge a few caps and dump the charge on launch.

Ed

1998\10\11@022913 by Dr. Ed Edmondson, Jr. Ph.D.

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Justin,

Your suggestion is duly noted.  Since I was in the Bells and Whistles mode for
the teen users age group that PIC would definitely have room for more
features.  Maybe even >> How about launching several (2 -6) rockets in
sequence.  The kids in the clubs do this sometimes. Like all launch at once or
in quick sequence.  Hmmm??

Ed

1998\10\11@023042 by James Cameron

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G'day Doc,

Dr. Ed Edmondson, Jr. Ph.D. wrote:
> Where do I find this RISK document you have referenced?

On the web at the URL http://catless.ncl.ac.uk/Risks or via USENET news
at news:comp.risks

Risks is a moderated discussion forum for issues relating to risks to
the public from computer systems, of all sorts.

It is fascinating reading, and well worth keeping up to date with, or
scanning if an issue is personally affecting me.  There is post-accident
review discussion and topical events.

--
James Cameron                                    (RemoveMEcameronKILLspamspamstl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800

1998\10\11@023507 by Dr. Ed Edmondson, Jr. Ph.D.

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Well, Mr. Supercat.....

They say KISS.  This might be the best and simplest safety idea yet.  Since
the rocket engines are only moderately dangerous.  I have never seen one
explode but the misfire and potential of being burned is more serious.

Anyone ever see one of the engines explode?  Look at some of the other
comments I have posted today and see what you think?  One main item is LED's
Vs Digital displays?

Thanks,
Ed

1998\10\11@024546 by Dr. Ed Edmondson, Jr. Ph.D.

picon face
Russell,

These are really great suggestions.  The reason for the PIC's is that I
already have a metric ton :-) of PIC related stuff.  I have two Picstart
Pluses, Microchips MP LAB software (the latest and greatest),  almost all of
Dontronics' SimmStik stuff, all kinds of LCD displays and nearly every thing
else in the way of parts and programmers.

I just need to get this thing designed (That is where your comments and
suggestions come into play), prototyped and built and delivered.  I plan on
getting the CCS C Compiler later this year.  Of course I realize the task
ahead of me since I have never designed any embedded (PIC or otherwise)
system.

Ed

1998\10\11@033019 by William Chops Westfield

face picon face
tick, tick, tick....

Come on people.  Safety design techniques applicable to space rated firing
systems for the Space Shuttle main engines, or blasting equipment that will
be used to detonate tons of explosives are NOT necessary for a model rocket
launcher (and indeed are not used in computer controllers for the
pyrotechnics industry, either.)  Most of your safety comes from more
common-sense techniques like not making the computer live while anyone is
nearby.

If I wanted to make a fancy countdown gadget for model rocketry, I'd put a
big pushbutton switch in series with the ignitor.  Then I'd have the circuit
send a small test current that simultaneously tested continuity, AND
actiavted the "countdown sequence."  So, press the button and hold for 5 to
10 seconds, and lights blink, sirens wail, and eventually the model
launches.  Want to abort the launh?  Let go of the push button and detect
that as well - if there's a failure and the software keeps counting down,
it's no big deal cause there's no longer a circuit for ignition current to
flow through anyway.  A additoinal keyswitch in the same series circuit
provides the positive interlock required by the safety code and appropriate
for the activity.

By the way, the way I read the model rocket safety code, they're pretty big
and an AUDIABLE countdown (at least 5 seconds.)  Around here (paranoid Ca,
most of the club launch system beep a piezo buzzer whenever the system is
armed (by LCO via footswitch), in addition to the countdown.  Want to add
bells and whistles?  This is a good place for electronic voice synthesis.
The other thing I'd add to be paranoid is some sort of sensort AT the clip
end of the system that detects voltage there (ie someone forgot to disarm
the keyswitch AND someone's leaning on the button.)

BillW

1998\10\11@033025 by William Chops Westfield

face picon face
Oh yeah.  Even "really bright" LEDs look pretty pitiful in bright sunlight.
Another good excuse for the voice add-on...

BillW

1998\10\11@033850 by William Chops Westfield

face picon face
   Anyone ever see one of the engines explode?  Look at some of the other
   comments I have posted today and see what you think?

You mean "Have you ever seen an Estes rocket motor explode in a manner
that would propose significant risk to someone standing a couple feet
away" ?

No, I don't think so.

Typical failure mode is that the black powder slug will detach from the
casing and fly out the front of the rocket (having torched the internals
pretty nicely.)  The (now discontinued) Estes Black powder E motors were
pretty famous for this.  Second common failure mode is to blow the nozzle
out.  Neither is a MAJOR hazard if you're beside the rocket instead of in
front or behind it.

I've heard that some of the larger motors (and not from Estes) have blown up
in a more spectacular (and dangerous) fashion...

BillW

1998\10\11@140200 by Dr. Ed Edmondson, Jr. Ph.D.

picon face
Bill:

Into model rocketry are we?  Looks like you have some knowledge of these
little Estes toys.  Some things which should be simple in theory always tend
to end up like an open can of worms.  Once opened, you are never able to
return the worms to the original can!

A rocket launcher for Estes type model rockets was the original idea.  All
five of my teenage boy and girls had to build and launch one of these as a
class project while in middle school.  Two of my boys still are interested in
these somewhat.

It was an asthmatic friend of my son who got me interested in building a
"better" or at least a neater one.  The unit Estes sells is great the first
few times (launches) but if you aren't rich enough to replace the 4 AA cells
after six to eight launches you will go through a lot of fuzes.  I built a
better launcher a couple of years ago and hung a big cap across the firing
line and that seemed to help a lot.  When the FET turned on it dumped the 6
volts and cap charge into the fuze.  We had a lot less misfires after this
little mod.

So now it appears we have a small unit constrained by the size of the
batteries used to power it.  An LCD display instead of LED's due to washout by
the sun light.  This display can also be used to display the battery status,
time or what ever.  It could also be back lit for late evening launches.  The
contrast and back light controlled by  digital pots?  I have an LCD
development kit from Wirz electronics.

 The keypad a 4 x 6 or 5 x 7 scanned matrix?  I have several friends who work
for companies who make membrane keypads and overlays.  A couple have indicated
they could make me up a couple if I can tell them what I want.  They can even
include the polarizer for the LCD display if that is the route to go.  I can
use a small mass produced plastic enclosure for the unit itself.

Has anyone used any battery charging / indication devices like BenchMarq make
for portable applications?  I have one built into my laptop battery pack.
This might be the way to go as far as monitoring battery status.  These can be
interfaced to a PIC or other processor.  I was looking at their web site and
they have a lot of neat items.

I still am looking for a clever way to dump the launch pulse down the wires to
the fuze?  I was thinking that using an opto isolator and high current FET
might work.  It would isolate the main circuitry from the firing circuit.  A
key interlock switch could be used to prevent accidental launch if the program
was set up as a one shot type of circuit.  If you don't return the key to the
off position after launch the unit will not launch again until reset.  This
could be coupled with the proverbial "Dead Man's" switch so the unit could not
be activated and then laid down to go check on something else or the rocket.
NO key turn + NO switch closure = NO Launch ability.

So now we are back to which PIC to use?  10 lines (??) for the key pad, a line
for the audio indicator, several lines for the LCD display, several lines for
the battery monitor, a line for the key switch, a line for the Dead Man's
switch, and ect.  That to me seems to be a lot of I/O?  A watch dog timer to
recycle the unit to the start up state if left unattended for "x" minutes.

The more I look the more I realize why embedded designers make so much money?
It is a never ending cycle.  Isn't it??

Regards,
Ed

1998\10\11@143828 by Mark Willis

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Dr. Ed Edmondson, Jr. Ph.D. wrote:
>
> <snipped>
>
> So now we are back to which PIC to use?  10 lines (??) for the key pad, a line
> for the audio indicator, several lines for the LCD display, several lines for
> the battery monitor, a line for the key switch, a line for the Dead Man's
> switch, and ect.  That to me seems to be a lot of I/O?  A watch dog timer to
> recycle the unit to the start up state if left unattended for "x" minutes.
>
> The more I look the more I realize why embedded designers make so much money?
> It is a never ending cycle.  Isn't it??
>
> Regards,
> Ed

 Good ideas on lots of alternate ways to make this work (Laptop
batteries aren't necessarily ideal though - this is a high current,
intermittent application, maybe a deep cycle "trolling" type battery
would be cheaper & easier as a power source?  And could be charged at
home on a normal charger.  Or just borrow power from someone's car <G>)
Or charge a low ESR cap with whatever battery (you do have at least the
length of the countdown to charge the firing cap., I've thought of
keeping that cap drained, except when the deadman switch is held down &
the firing key in "Armed"...)

 You can cut the number of I/O lines down by increasing parts count, by
using a shift register or a Johnson counter you can scan several rows or
columns of a keypad with two (or even one with a few more parts!) I/O
line.  (Your choices here <G>  Could use 6 lines to the shifter/johnson
counter, and 4 to the pic, to just use 5 or 6 total PIC I/O lines for
the keyboard, that cuts things down somewhat - at the cost of one more
IC.)

 Think of having a wind indicator near this launch pad, also (Robin has
asthma, I wouldn't want her downwind from a launch plume!  Black powder
smoke, would not be a good inhalant...)

 (A spare Maxair inhaler taped to the launch console?  It's an idea...
Robin LOVES that stuff, she can give it to herself - wonderful!)

 Mark

1998\10\11@145730 by shadedemon

picon face
Dr. Ed Edmondson, Jr. Ph.D. wrote:
> It was an asthmatic friend of my son who got me interested in building a
> "better" or at least a neater one.  The unit Estes sells is great the first
> few times (launches) but if you aren't rich enough to replace the 4 AA cells

 While I see the point of this being his only recreation,
no matter how nice you make the unit, it's function will be
the same and become routine almost instantly.  I can't help
but feel it would be a better service to him to make a good
straightforward launch controller and then concentrate on a
good data logging system, as several others have discussed
in the past.  Don't get me wrong, most of the stuff you're
proposing isn't that hard really, so go at it, but bells and
whistles are just that, and don't age very well.  The data
logging and science behind it will be a much more sustained
interest.  Even more than that, if he's over the age of 6 or
so, and especially if 10 or more, you should hook him up
with a simple pic programmer and some 16F84s and simple demo
boards and get him on the list.  Even more sustained
interest, and you'd be amazed at what a kid can learn and
enjoy, more so if they don't have other outlets.  Heck I
know a little girl who knows more about windows and what
goes on behind it than most adults, and she is only 7..

This
> could be coupled with the proverbial "Dead Man's" switch so the unit could not
> be activated and then laid down to go check on something else or the rocket.

 "Laid down" is the key idea.  Two or three small mercury
switches in series arranged to give only a medium window
where all of them make when the controller is held
diagonally or vertically is the way to go..  Just make it
broad enough to not have misfires but narrow enough to not
be able to lay it down and have any chance of both making.
And sample it with a pic pin often enough and ignore no
makes for <1/4 second or so, so a shaky hand doesn't mess
things up..
Alan

1998\10\11@150107 by Dave VanHorn

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>So now it appears we have a small unit constrained by the size of the
>batteries used to power it.  An LCD display instead of LED's due to
washout by
>the sun light.  This display can also be used to display the battery
status,
>time or what ever.  It could also be back lit for late evening
launches.  The
>contrast and back light controlled by  digital pots?  I have an LCD
>development kit from Wirz electronics.


Are you aware of rec.model.rockets?  Lots of rocket folks there.

My best suggestion would be to place the ignition battery at the pad,
and use a relay to close that circuit.
Continuity can be indicated by running a couple mA through the firing
circuit. You only have to worry about current when you start using
flashbulbs and thermalite.

A local switch at the pad gives you continuity/fire control. In the
open position, the safety switch and the firing relay are shunted by
the continuity resistance, plus an indicator. I use a superbright
green LED.
When you are ready, close the safety switch and walk back to the
controller.  With this arrangement, nothing you do at the controller
matters, until the safety switch is closed. You could remote that
switch to say 10' from the pad, so that even if everything goes wrong,
you're at a safe distance when it ignites.

For ABCDE engines, they recommend 10' of wire, but since I also fly
G,H,I motors, I use 100'  Even with the smaller engines, being farther
away from the pad makes it easier to track them.  Your asthmatic could
probably use the extra distance as well.   Since you are using a relay
at the pad, the extra wire length makes no difference electrically.  I
use that 100' roll-up telephone cable that Radio-Shack carries.

The controller can now be as fancy as you like, and you don't have to
use "life-support" precautions in building it.  I would though,
include a mechanical key switch (not those ones from PC cabinets) in
series with the firing circuit.

With the four conductors available in the phone cable, you can carry
ground, power, fire and continuity between the relay box and the
controller.

A 12V gell cell, even as small as 1AH, will fire modroc igniters just
fine.

For deluxe brownie points, add plug-in clipsets, so you can replace
them with a spare, or with different ends for "copperhead' igniters.

1998\10\11@150311 by Dave VanHorn

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Sorry, that was rec.models.rockets  :)

1998\10\11@155602 by Mark Willis

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Wanted to also mention:  I've seen more than one good launchpad design
where the battery is used to weight the launchpad, with a straight relay
in the launch base to fire the rocket (Put some metal sheet under the
rocket exhaust <G>) - then the wires to the control head do not have to
be heavy duty wire.  Putting the battery 5-10 feet from the launchpad &
a safety switch inline at that battery, might be good (put the countdown
display atop the battery? <G>)  Short heavy-gauge wires for high
currents is good <G>  Switch the relay (SSR?) current not the entire
current...

 Also, for fuze continuity (I always call them ignitors to be clearer)
I can say that an LED in series with a nice resistor works pretty well
(15-20 mA is nowhere near enough to touch off an ignitor.)  You could
wire these across the fire switch, or the relay contacts if you use a
remote relay to fire the ignitor.  Just be careful here to put the
resistor in the relay-end box, as a heavy short across -this- wire could
otherwise cause an accidental launch!  An optoisolator for remote
reading of continuity, isn't a bad idea at all...

 (Socket those optoisolators, too, in most designs, folks.  They *do*
fail, not here so much as in high-spike situations, where optoisolation
is necessary, and it's annoying to have to de-solder in the field.
Pulling a chip from a  socket & replacing it, OTOH, isn't half bad <G>)

 Mark, mwillisSTOPspamspamspam_OUTnwlink.com

Dr. Ed Edmondson, Jr. Ph.D. wrote:
>
> <snipped>
>
> The wire shipped with the ESTES (the rocket kit, engine and fuze manufacturer)
> is nothing more than gray zip cord (2 conductors) like they use to wire CHEAP
> <snipped>

1998\10\11@160020 by Mark Willis

flavicon
face
Dr. Ed Edmondson, Jr. Ph.D. wrote:
>
> <snipped>
> Anyone ever see one of the engines explode?  Look at some of the other
> comments I have posted today and see what you think?  One main item is LED's
> Vs Digital displays?
>
> Thanks,
> Ed

 One, once.  It may well have been tampered with, knowing the engine's
owner.  (I'd say 95% probability.)  Far more failures to ignite with a
perfectly good ignitor (I'm guessing that they coat the engines for so
much safety that they're *really* tough to ignite, to make sure they're
safe.)  Used to love this sport, got too busy to play lately!

 I've seen worse problems by far from model aircraft engines (more
likelihood of burns & "prop-chop" etc.)

 Mark, spamBeGonemwillisSTOPspamspamEraseMEnwlink.com

1998\10\11@180309 by Alan Vogel

flavicon
face
How about placing a small filament lamp in series with the ignitor (mounted
in the hand-held firing box).  The voltage drop across the lamp prevents the
fuse from igniting until a momentary switch is pushed that shorts the bulb.

Alan
-----Original Message-----
From: Dr. Ed Edmondson, Jr. Ph.D. <KILLspamDreaejrphdspamBeGonespamAOL.COM>
To: EraseMEPICLISTspamEraseMEMITVMA.MIT.EDU <@spam@PICLIST@spam@spamspam_OUTMITVMA.MIT.EDU>
Date: Saturday, October 10, 1998 11:32 PM
Subject: Re: PIC_k You Brains


[snip]
>I am sure this will bring out a few other questions.  How about a clever
way
>to detect fuze continuity without igniting the fuze?  Or maybe, using a
>circuit to charge a few caps and dump the charge on launch.
>
>Ed
>

1998\10\11@193417 by Mark A Moss

picon face
There are three "potentially" dangerous things I have seen small model
rockets do.  First, poorly designed rockets have had the tendency to fly
in unpredictable directions: up, down, even parallel to the ground.
There is nothing the launch device can do to prevent this.  Second,
engines that are not properly secured have fallen out during flight.
Again, there is nothing that the launch device can do to prevent this.
The last hazard that I have seen is when a rocket engine has ignited when
someone is too close to the pad.  Generally, this is because that they
are not following safety procedures.

Most model rocket launchers have two switches and a light bulb.  One
switch is closed by inserting a "key" into a jack in the launcher.  This
completes the circuit and allows a low current to flow through the light
bulb and the ignitor.  This give a visual go/no-go indication of the
ignitor.  The second switch is a push button in parallel with the lamp.
Pushing this buttons shorts the lamp and allows a large current (about
3A) to light the ignitor.  The large current that is required to heat the
ignitor to its ignition point probably nulls the possibility that a
strong RF field could ignite the rocket.

What I would do is this.  In addition to all the bells and whistles, I
would have the PIC drive two relays.  One would be placed in series with
the "key" switch.  This way, no voltage or current would exist at the
clips until the PIC wanted it to.  The second relay would be placed in
series with the push button switch.  With this setup, the only way the
rocket would launch is if both relays were closed, the key was in, and
the button was being pushed.   As long as proper safety procedures were
followed, it would be difficult to have any problems with unexpected
launches.


Mark Moss
Amateur Radio Operator, Technician, and General Tinkerer

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1998\10\11@193432 by Dave VanHorn

flavicon
face
>How about placing a small filament lamp in series with the ignitor
(mounted
>in the hand-held firing box).  The voltage drop across the lamp
prevents the
>fuse from igniting until a momentary switch is pushed that shorts the
bulb.


This is safe for estes and copperheads, but I'm not sure where it
falls with other types. Lamp resistance is somewhat variable anyway.
An LED and resistor makes a much more predictable choice.

1998\10\12@030324 by ruben

flavicon
face
Hello Ed.

> Ruben:
>
> Thank you very much for the contribution on the safety mechanism for fuzing
> and accident prevention.  Since these PIC's are so very inexpensive the
> thoughts you suggested are really not far out of the realm of consideration.
> I do see where it might take a lot of program development.  Would you use
> something like I2C to communicate between the two processors?  Or is there a
> simpler or better method for two PIC's to cross communicate with one another?
>
> Ed

When I have done this I have just used two I/O lines, one clock and the other
data. The program cycle of both processors looks something like this:

1. Synch. Synchronize channel A with channel B (use clock or data line for
this) so that the timing between the two chanels are known.

2. Sample. Set up I/O lines and sample inputs. Save info for eval stage.

3. Eval. Evaluate sampled inputs and take appropriate actions. Sicne each
cycle generaly takes a couple of milli seconds it's easy to debounce inputs.

4. Communication. Channel B waits for info from channel A by reading a
predefined number of data bits on the falling edge of clock. Channel A then
waits for info from channel B. Since both channels are in synch and
communication only takes place in known timeslices and the number of data
bits transfered is low this works fine. The channel that sends controls the
communication I/O lines, the other channel sets these to inputs. To minimize
data error every bit is sent as two bits which can be either '01' or '10'. Any
other value is an illegal combination.

5. Activating safety outputs if they should be on.

6. Memory tests and other processor testing.

7. Go back to top.

Another thing about the safety outputs. To minimize the risk of the output being
activated if the program malfunctions (due to EEPROM failure, brownout, EMC
etc) is to never write to the portbit directly (eg bsf portx,safteyoutput) but
instead calculate the adress and bit of the output during the program cycle. For
instance at top of the cycle clear a register used for calculating the adress an
d
at appropriate stages in the program flow increment this register. If the progra
m
works Ok the register should contain a known value when the safety output
should be set (or toggled) manipulate this known value with a constant if needed
to get the desired value, extract the bit information and put the calculated por
t
adress in FSR and activate the output by indirect adressing. Make it even safer
and use two registers for calculating the portbit - use a cycle counter and at t
he
top of the cycle load the adress calculation register with different values for
different values of the cycle counter. The whole meaning of this is not to have
any code that directly manipulates the safety output.

As You have seen on this list though, the safety issues for this project could
probably be keept outside the electronics and processors alltogether by
disabling it (no power) with key switches or something when no launch should
be done.


--------------------------------
Ruben Jvnsson
spamBeGonerubenspamKILLspam2.sbbs.se
--------------------------------

1998\10\12@085756 by Peter L. Peres

picon face
On Sun, 11 Oct 1998, Dr. Ed Edmondson, Jr. Ph.D. wrote:

> little Estes toys.  Some things which should be simple in theory always tend
> to end up like an open can of worms.  Once opened, you are never able to
> return the worms to the original can!

How nice that some people notice this early ;)

> I still am looking for a clever way to dump the launch pulse down the wires to
> the fuze?  I was thinking that using an opto isolator and high current FET
> might work.  It would isolate the main circuitry from the firing circuit.  A

Just thought I'd mention some things books say about drivers for such,
ahem, things:

- The battery voltage is to be too low to fire the fuse if connected
directly to it, for any length of time.

- The output to the fuse should be AC coupled (transformer secondary) and
matched to the line with suitable resistors.

- The a.c. generating device should be run off a charge storage device
(capacitors) charged at a voltage higher than the battery voltage.

- The a.c. generating device should not be able to operate from un-boosted
battery voltage.

- The firing should occur after a large amount of cycles in the a.c.
generating device (i.e. a few cycles are not enough).

- The previous point opens the possibility of precision timed firing
sequences (computer in each fuze counts pulses before firing).

- None of this is new, the magneto detonators used way back before WW2 all
worked like this, excepting the part on batteries (used none) and the part
on precision firing (?).

There is much more. This I've culled from mining & prospection explosive
handling textbooks. They should be available in a university bookstore.
Also describes fuzes and other interesting data, such as safety distances
and procedures. Compulsory reading for rocket people imho. <g>

hope this helps,

Peter

1998\10\12@112041 by Tom Handley

picon face
  Peter, this really does'nt apply to model rockets that are available here.
The engines are solid propellant manufactured to very strict standards and are
very similar to the Space Shuttle SRBs, etc. I can understand why such a hobby
is not available in Israel. In this country, you can go to most any hobby shop
and buy kits, parts to build rockets, and engines. Still, if your country would
allow the hobby under some kind of control (ie: engine purchase for educators),
it can be very educational, fun, and safe.

  I'm working on a response to Ed but, as is typical of this group, there has
already been many excellent replys. I have kind of a unique perspective as I
started back in the 60's with Estes rockets and engines. Back then they still
used fuzes that you lit with a match... Then the wire ignitor. Now days they
coat the ignitor with a material that improves the reliability of ignition.
I love this topic and this message is the first of a `flood' of messages that
I want to discuss from Ed's application to PIC-based payloads ;-)

  - Tom

At 02:24 PM 10/12/98 +0000, Peter L. Peres wrote:
>On Sun, 11 Oct 1998, Dr. Ed Edmondson, Jr. Ph.D. wrote:
>
>> little Estes toys.  Some things which should be simple in theory always tend
>> to end up like an open can of worms.  Once opened, you are never able to
>> return the worms to the original can!
>
>How nice that some people notice this early ;)
>
>> I still am looking for a clever way to dump the launch pulse down the
wires to
{Quote hidden}

1998\10\12@120643 by Peter L. Peres

picon face
On Mon, 12 Oct 1998, Tom Handley wrote:

>    Peter, this really does'nt apply to model rockets that are available here.
> The engines are solid propellant manufactured to very strict standards and are
> very similar to the Space Shuttle SRBs, etc. I can understand why such a hobby
                     ^^^^^^^^^^^^^^^^^

Ouch. I get the point but that was not such a good example imho. If the
failure rate of model rocket engines would equal the SRBs that hobby would
have disappeared a long time ago.

> allow the hobby under some kind of control (ie: engine purchase for
> educators), it can be very educational, fun, and safe.

I agree. But...

> started back in the 60's with Estes rockets and engines. Back then they still
> used fuzes that you lit with a match... Then the wire ignitor. Now days they
> coat the ignitor with a material that improves the reliability of ignition.

Actually I did not SAY that I did not DO such things. Small lightbulbs
with the glass removed and embedded in alcohool-wetted black powder make
excellent ignitors in my memory (after drying)... They are fired with
about 4 * over-voltage and reach the melting temperature of Tungsten, plus
produce a small arc when they burn through. Just like modern fuze caps ;)
Don't try this at home please, getting the variables right involves some
amount of destruction.

Peter

1998\10\12@135654 by paulb

flavicon
face
Dr. Ed Edmondson, Jr. Ph.D. wrote:

> The contrast and back light controlled by  digital pots?

 No way!  These are controlled by PWM outputs from the PIC.

> I was thinking that using an opto isolator and high current FET might
> work.

 Why do people have this fetish for optocouplers?  Reliability. let
alone costs, dictates you only want one battery if at all possible.

> So now we are back to which PIC to use?  10 lines (??) for the key
> pad,

 Ten lines?  What waste!  I presume your reference to 7 by 5 or 35
buttons suggests an almnost full alpha(-numeric) keypad, though I can't
for the life of me figure why.  At worst, use a CMOS 10-output counter
to strobe ten rows and sense three or four inputs.  The counter only
needs reset and clock, which can be multiplexed with other functions.

 I think we can easily restrict this to the 16F84!

> several lines for the LCD display,

 Six or seven, all bar one multiplexed with other things.

> A watch dog timer to recycle the unit to the start up state if left
> unattended for "x" minutes.

 Eh?  This is a software feature surely?

> The more I look the more I realize why embedded designers make so much
> money?

 Well, they *should*!
--
 Cheers,
       Paul B.

1998\10\15@065000 by Pavel Korensky

flavicon
face
At 07:06 10.10.1998 -0700, you wrote:
>I think any recommendation regarding missile safety is incomplete if we dont
>also recommend dual launch switches, located at least 6 feet apart, that
>must be pressed simultaneously.  That way, a single crazed rocketeer cant
>launch your rocket.
>

I thought that the talk was about hobby rocket models, not about the
trans-continental A or H missiles.
But seriously, if high safety is really necessary, maybe the control
circuit which will monitor the function of LEDs should be included. Once, I
designed the bomb countdown timer (for the police squad, not for the
terorists :-) and there was two LEDs green and red. When the timer was in
idle state, both LED was switched off. When the timer was in Ready state,
green LED was on. When timer was on Armed state, red LED was on. It was
necessary to include the test circuit which monitored the red LED current,
just to be sure that LED is not broken. It sounds funny, but during the
test phase, I met this condition once. Red LED suddenly died and I tought
that timer is in Ready state. Suddenly the relay clicked ....

PavelK

**************************************************************************
* Pavel KorenskyÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
* DATOR3 LAN Services spol. s r.o.ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
* Styblova 13, 140 00, Prague 4, Czech Republic      ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
*ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
* PGP Key fingerprint:Ê F3 E1 AE BC 34 18 CB A6Ê CC D0 DA 9E 79 03 41 D4 *
*ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
* SUMMA SCIENTIA - NIHIL SCIREÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ *
**************************************************************************

1998\10\15@140412 by William Chops Westfield

face picon face
The major safety concern with model rocketry and automatic launch equipment
is that model rocketry is currently safe enough to share "play space" with
other activities, given only peripheral awareness of the rocket launch.  If
Joe Schmoe's frisbe goes awry and he runs into the launch area during the
countdown, you must be able to abort the launch instantly.

Main causes of injuries during model rocket activities: tripping while
chasing rocket and not watching where feet are going, poking yourself on
the launch rod, falling while climbing trees to recover rocket, electrocution
while trying to recover rocket from power lines.  The number of people that
have been burned by rocket exhaust or hit and injured by flying rockets is
miniscule - lower than the number of kids killed playing little league
baseball...

BillW

1998\10\23@144459 by John Payson

flavicon
face
>>
Oh yeah.  Even "really bright" LEDs look pretty pitiful in bright sunlight.
Another good excuse for the voice add-on...
<<

If you can find them, "flip-mechanical" displays are excellent
in any light condition and generally have pretty reasonable
current requirements.  Not sure about surplus availability,
though--when new they probably cost a bundle.

Also, I go along 100% with much of what others have said re
safety: don't give launch authority to the PIC (except when
a button is being held down).  And then, of course, make sure
you clearly mark the thing and tell people never to push the
button if they're not expecting a launch.

Of course, some bozo will probably still manage to injure
himself by pusing the button when he doesn't think the thing
will really launch, but all too many bozos (even on occasion
police officers) pull the triggers on firearms and somehow
don't think they might fire ("I didn't know the gun was
loaded".)  Too bad so many people in this world have no clue
about how to use a modicum of safety-related common sense.




Attachment converted: wonderland:WINMAIL.DAT 2 (????/----) (0001BBDE)

1998\10\23@221358 by Mark Willis

flavicon
face
John Payson wrote:
> <snipped>
> Of course, some bozo will probably still manage to injure
> himself by pusing the button when he doesn't think the thing
> will really launch, but all too many bozos (even on occasion
> police officers) pull the triggers on firearms and somehow
> don't think they might fire ("I didn't know the gun was
> loaded".)  Too bad so many people in this world have no clue
> about how to use a modicum of safety-related common sense.

 From what a friend said about one police officer he knows who got to
buy himself a new TV due to an accidental discharge, it sounds like bad
habits cause "A.D.'s" - this police officer practiced dry firing with
his revolver properly unloaded for a time (which is good practice for
trigger control!) but then proceeded to, absolutely stupidly, go back to
his storage location, reload the revolver & then went back to the den to
try to continue to dry fire...

 This was, somewhat understandably, hard on the TV!  (Geraldo must've
been on?)  Stupidity/Bad habits hand in hand here...  Ack!  Where'd his
sanity go?!?

 Fortunately nothing damagable was in the line of fire besides the TV &
a wall, BUT...

 Always assume a rocket, firearm, car, wire, or whatever is live, and
potentially dangerous, unless you have really GOOD reason to believe
otherwise <G>

 Mark, .....mwillisspam_OUTspamnwlink.com


'results: the Project that Ate my Brain'
1999\07\07@173643 by Alice Campbell
flavicon
face
Hello all,

My first pic project hits the street (well, a dump) tomorrow or the
next day.  I owe it all to you guys.

For the record, it took about 1 year from concept to the
Al-o-Tron Mark 1 landfill datalogger.  Armed only with enthusiasm and
a ham radio license, i learned to program the 16c84 in assembly,
including watchdog timeouts, using reset as interrupt, and
designed the circuit, including 8-bit adc 0831, memory 93c56, figured
out how to make the 33khz crystals work, wrote a 300-baud serial
interface, hooked in a 15 psi sensym pressure sensor, learned to
create a temperature compensation circuit for it, built my first
instrumentation amplifier, built an infrared link that doesnt work
too well yet, produced my first circuit board, and put in a s81350hc
ldo regulator.  i plan to upgrade the adc to 12 bits when i locate an
8-pin one.  It runs off 9volts because thats all i know how to do
yet, but when i figure out switchers i will change it to 2AAs.

This has been an incredible experience.  I couldnt have done it
without you.  Special thanks to

David Tait
Dave Johnson
Don Mckenzie
Glenn Torr
Jose Maria Goni
Paul Webster
Peter Peres
Regulus Berdin
Russel McMahon
Sean Breheny
Thomas Mcgahee
Tony Nixon
Wagner Lipnharski

its been an honor to eavesdrop on all you swells.
               clrwdt
hooray  its working
                its working
                its working
                its working
               goto    hooray

end
alice

1999\07\07@180149 by kfinney

picon face
What ? No ESP interface ?  :.)

Congratulations !

-----------------------------------------
Kenneth C. Finney
=========================================
Wilkes Associates, Inc.
Software Engineering - Embedded Systems
Design & Development - Project Management
=========================================
Office:  (416) 445-9224
Mobile:  (416) 453-6400
-----------------------------------------

> {Original Message removed}

1999\07\07@200440 by Dave VanHorn

flavicon
face
> It runs off 9volts because thats all i know how to do
> yet, but when i figure out switchers i will change it to 2AAs.


Run, do not walk, to linear technology (odd name for a switcher mfgr)
They have excellent parts, and documentation.

1999\07\07@201729 by Sean Breheny

face picon face
Congratulations, Alice!

That sounds like a really interesting and challenging project. Is it
commercial(I would guess that it is)? If not, is there any chance that you
might document it on a web page?

Sean


At 12:08 AM 7/7/99 PST, you wrote:
>Hello all,
>
>My first pic project hits the street (well, a dump) tomorrow or the
>next day.  I owe it all to you guys.
>

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
TakeThisOuTshb7.....spamTakeThisOuTcornell.edu ICQ #: 3329174
________________________________________________________
NetZero - We believe in a FREE Internet.  Shouldn't you?
Get your FREE Internet Access and Email at
http://www.netzero.net/download/index.html

1999\07\07@203634 by Alice Campbell

flavicon
face
Thanks Sean,

um, i dont know what to do next.  i built it for work, but on my own
time.  there isnt exactly an up-to-date schematic, and the code would
have people ROTFL.  its nowhere near commercial quality, if only
because of the green wire jumpers that hold it together and the
rubber-band strain relief for the battery clip wire.  and i have no
idea how to do a website, and dont know if my brain can handle it.

virtual beer for all if allowed by your religion.  root beer
otherwise.

alice
KA7DYQ


> Congratulations, Alice!
>
> That sounds like a really interesting and challenging project. Is it
> commercial(I would guess that it is)? If not, is there any chance that you
> might document it on a web page?
>
> Sean
>
>

1999\07\08@021148 by Bob Wake & RenŽe McMeeken

flavicon
face
Dave VanHorn wrote:
>
> > It runs off 9volts because thats all i know how to do
> > yet, but when i figure out switchers i will change it to 2AAs.
>
> Run, do not walk, to linear technology (odd name for a switcher mfgr)
> They have excellent parts, and documentation.

No, go to Maxim, they have a +5V boost regulator that is specifically
made to run from 2 AA's

1999\07\08@111417 by Jack Shidemantle

flavicon
face
Congratulations Alice, glad to hear things worked out for you. I have been
on this list for about a year now and while I've done two PIC projects I
have done very little of Êthe software myself, Êso will look for help from
the rest of you when I begin the next project not having a software
assembly person to rely on. Makes me nervous to think about it.

@
Sent by: pic microcontroller discussion list <TakeThisOuTPICLISTKILLspamspamspamMITVMA.MIT.EDU>
07/07/99 12:08 AM PST
Please respond to pic microcontroller discussion list

To: .....PICLISTspamRemoveMEMITVMA.MIT.EDU
cc:
bcc:
Subject: results: the Project that Ate my Brain


Hello all,

My first pic project hits the street (well, a dump) tomorrow or the
next day. ÊI owe it all to you guys.

For the record, it took about 1 year from concept to the
Al-o-Tron Mark 1 landfill datalogger. ÊArmed only with enthusiasm and
a ham radio license, i learned to program the 16c84 in assembly,
including watchdog timeouts, using reset as interrupt, and
designed the circuit, including 8-bit adc 0831, memory 93c56, figured
out how to make the 33khz crystals work, wrote a 300-baud serial
interface, hooked in a 15 psi sensym pressure sensor, learned to
create a temperature compensation circuit for it, built my first
instrumentation amplifier, built an infrared link that doesnt work
too well yet, produced my first circuit board, and put in a s81350hc
ldo regulator. Êi plan to upgrade the adc to 12 bits when i locate an
8-pin one. ÊIt runs off 9volts because thats all i know how to do
yet, but when i figure out switchers i will change it to 2AAs.

This has been an incredible experience. ÊI couldnt have done it
without you. ÊSpecial thanks to

David Tait
Dave Johnson
Don Mckenzie
Glenn Torr
Jose Maria Goni
Paul Webster
Peter Peres
Regulus Berdin
Russel McMahon
Sean Breheny
Thomas Mcgahee
Tony Nixon
Wagner Lipnharski

its been an honor to eavesdrop on all you swells.
Ê Ê Ê Ê Ê Ê Ê Êclrwdt
hooray Êits working
Ê Ê Ê Ê Ê Ê Ê Ê its working
Ê Ê Ê Ê Ê Ê Ê Ê its working
Ê Ê Ê Ê Ê Ê Ê Ê its working
Ê Ê Ê Ê Ê Ê Ê Êgoto Ê Êhooray

end
alice

1999\07\08@120819 by eplus1

flavicon
face
Please document it if only as an entry in the "most hacked together thing
that actually works" contest. Reading others code and looking at new curcits
is the best way for all of us to learn. I want to learn what new people
misunderstand, for example.

Web sites are easy. If you have email, just go to http://www.geocities.com or
http://www.yahoo.com and sign up for a free site. There is lots of help and lots of
free tools to get started. I personally like http://www.aolpress.com as a super
simple, quick, "looks just like a regular text editor but puts out HTML and
its free and it will ftp if you File / Save as...
ftp://RemoveMEmembernamespamspamBeGoneservername.com/directory/file" tool.

James Newton, webmaster http://get.to/techref
spamBeGonejamesnewton@spam@spamspam_OUTgeocities.com <TakeThisOuTjamesnewtonspamspamgeocities.com>
1-619-652-0593 phoneÊ



> {Original Message removed}

'ALICE CAMPBELL: the Project that Ate my Brain'
1999\07\11@120545 by Thomas McGahee

flavicon
face
Alice,
I have been away from home this past week or I would have
sent an e-mail sooner.

Congratulations on the successful completion of the Al-o-Tron
Mark 1 landfill datalogger!!!

>From your e-mail it sounds like you have been very busy
(enthusiastically busy, which is the best kind of busy-ness there
is!!).

I was pleasantly suprised to see my name amongst the list of persons
you extended special thanks to. Thanks for the thanks :)  It always
makes my day when I discover that my posts have been helpful to
someone.

If I can ever be of further assistance in any way, please do not
hesitate to ask.

Now that you have the project finally running you get to have the
joy of "modifying" it! The company LINEAR makes a number of decent
switching power supply ICs, as does MAXIM. In fact, your greatest
difficulty will probably not be in finding adequate ICs, but in
choosing which one to use!

Fr. Tom McGahee

----------
> From: Alice Campbell <1502amcEraseMEspamLO.SCSENG.COM>
> To: RemoveMEPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU
> Subject: results:  the Project that Ate my Brain
> Date: Wednesday, July 07, 1999 4:08 AM
>
Hello all,

My first pic project hits the street (well, a dump) tomorrow or the
next day.  I owe it all to you guys.

For the record, it took about 1 year from concept to the
Al-o-Tron Mark 1 landfill datalogger.  Armed only with enthusiasm and
a ham radio license, i learned to program the 16c84 in assembly,
including watchdog timeouts, using reset as interrupt, and
designed the circuit, including 8-bit adc 0831, memory 93c56, figured
out how to make the 33khz crystals work, wrote a 300-baud serial
interface, hooked in a 15 psi sensym pressure sensor, learned to
create a temperature compensation circuit for it, built my first
instrumentation amplifier, built an infrared link that doesnt work
too well yet, produced my first circuit board, and put in a s81350hc
ldo regulator.  i plan to upgrade the adc to 12 bits when i locate an
8-pin one.  It runs off 9volts because thats all i know how to do
yet, but when i figure out switchers i will change it to 2AAs.

This has been an incredible experience.  I couldnt have done it
without you.  Special thanks to

David Tait
Dave Johnson
Don Mckenzie
Glenn Torr
Jose Maria Goni
Paul Webster
Peter Peres
Regulus Berdin
Russel McMahon
Sean Breheny
Thomas Mcgahee
Tony Nixon
Wagner Lipnharski

its been an honor to eavesdrop on all you swells.
               clrwdt
hooray  its working
                its working
                its working
                its working
               goto    hooray

end
alice


'Brain dead PIC programmer'
1999\08\23@063755 by steveb
flavicon
face
Is anyone aware of a stand-alone, brain-dead, PIC chip cloner ?

I'm looking for something that can be used in a small production
environment, by unskilled workers. What I invisage is a socket for a
master part and a ZIF for the part to be programmed. Put the master
into the socket and the device to be programmed in the ZIF. Press the
button and wait for the light to come on. Put the next chip in.
No PC required.
In this instance I am looking for a 16C54 cooker but I don't recall
seeing anything along these lines.

Has anyone else ?
======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
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======================================================

1999\08\23@121229 by Dan Larson

flavicon
face
I have a heavily modified version of a YAPP (not YAP) programmer
that downloads via a true RS-232 connection.  I have source
for the firmware and the programmer software which I have
modified form the original.  The design uses a 16C54 or 16F84
to do the comms and the burning.  I modified it to burn
16F877's.

I suppose that someone could start with the same programmer,
add a serial EEPROM to store the binary image downloaded by
the PC and burn as many PICs as you wish from the downloaded
image.  It would sure as heck save time download time over
the serial port on subsequent burns.  A 32K or larger serial
EEPROM could store several images to select from for
different devices.  Add some LEDs to indicate pass/pail, and
some kind of display to indicate which device and image
are selected.

I have no use for such a thing, but it would seem like an
interesting project.  I'd rather spend my time working on
my robot projects.  I only burn 'em one at a time any way.

I got it from http://www.picpoint.com

Look for YAPP!  the web site was under construction last time
I looked so you may not be able to get to the archive.  If
you cannot find the project anywhere here is the author:


Sergio Tanzilli
email: EraseMEtanzospam@spam@tin.it


On Mon, 23 Aug 1999 22:25:05 +1200, Steve Baldwin wrote:

{Quote hidden}

1999\08\23@165320 by Harold Hallikainen

picon face
On Mon, 23 Aug 1999 22:25:05 +1200 Steve Baldwin <spamBeGonestevebEraseMEspamKCBBS.GEN.NZ>
writes:
>Is anyone aware of a stand-alone, brain-dead, PIC chip cloner ?
>
>I'm looking for something that can be used in a small production
>environment, by unskilled workers. What I invisage is a socket for a
>master part and a ZIF for the part to be programmed. Put the master
>into the socket and the device to be programmed in the ZIF. Press the
>button and wait for the light to come on. Put the next chip in.
>No PC required.
>In this instance I am looking for a 16C54 cooker but I don't recall
>seeing anything along these lines.
>
>Has anyone else ?

       And it sets the code protect bits on the copies?  Not cheap, but
we have an old DOS computer used for a variety of things in production.
A simple menu with batch files calls the DOS PROMATE program to send the
hex file to the ProMate and program the first chip (with code protect!).
After that, they just keep hitting F2 (Pgm) on the ProMate.

Harold


Harold Hallikainen
haroldspamBeGonespamhallikainen.com
Hallikainen & Friends, Inc.
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'Just brain training. Rotating nibbles inside of by'
2000\04\19@185513 by Dmitry Kiryashov
flavicon
face
Hi guys.

Last topic about rotating two logical ones in porta burned imagination about
possible situations with nibble rotations in single byte.

So I'm trying to play with this situations. Interesting to involve others ;)
It maybe nibble rotations, two or three or more groups of bit in single byte
that rotated by some law and periodically return to initial positions. It will
be interesting to discuss what is practical usability of such operations.

Two examples to start.

a) abcd.efgh -> bcda.fghe

       rlf     X,W
       rlf     X,F     ;bcdefgha

       swapf   X,W     ;...a...e
       xorwf   X,W
       andlw   0x11    ;...<a^e>...<e^a>
       xorwf   X,F     ;bcdafghe

b) abcd.efgh -> dabc.hefg

       rrf     X,W
       rrf     X,F     ;habcdefg

       swapf   X,W     ;d...h...
       xorwf   X,W
       andlw   0x88    ;<d^h>...<h^d>...
       xorwf   X,F     ;dabchefg

WBR Dmitry.


'Strain the brain'
2000\05\17@211519 by Tony Nixon
flavicon
picon face
Heaven forbid, I had to design a simple circuit, but this time I
couldn't use a PIC. It would be an ideal little job for a 508 but I
don't have one handy.

The circuit needs to have a relay operated when power is applied, but
when it gets a -ve going 1/2 second pulse, let the relay stay operated
for another 40 seconds then release it permanently.

The software would be quite simple, but what a brain strain going back
to discrete digital again to accomplish the same task when I haven't
fiddled with TTL or 4XXX CMOS for what seems like ages.

I ended up using 3/4 of a 4093 quad NAND gate. It's amazing when you are
out of practice, how long it takes to come up with a simple solution
without software.

--
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Tony

http://www.picnpoke.com
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'[pic]: F87X code protection on brainstorm'
2000\08\30@120652 by Simon Nield
flavicon
face
Good idea Bob.
Would seperate write and read protect fuses solve the problem ? The only way to clear these bits
being to erase the device?

The only problem I can see with this is verifying flash writes, but this could be done by a return
value from the flash write hardware - i.e. there is hardware checking the write was ok.
(have to be careful here that a chunk of code can't do a hacked read by writing a byte and then not
waiting for the write to complete - or not charging up the flash circuit with the writes of 0x55 and
0xaa first - repeat up to 256 times per byte and you know what the byte is - it's the value that
appeared to program correctly)

If you don't have seperate controls for read and write then you can always download a 'rogue' new
program that just overwrites the first byte with a jump to a routine to read all of memory. Do this
twice and you can read all of the memory in a chip bar the first byte.

Personally I think I would just try and avoid having a flash updatable PIC with 'sensitive' code on
it. If you are letting the end user flash the new code on to the pic then they can always hack your
protection system (if you have one) and find out what the new code you are downloading is. If they
are having to return the device to you for you to update it or you are sending someone out in the
field to update it, then the cost of a socket and a few otp chips is going to be a lot less than the
cost of your employees time anyway.

Regards,
Simon

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'[OT]: ACK! Sorry. Brain-scrambled browsers...'
2000\10\07@165036 by Mark Willis
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Can anyone subscribed to [other] tell my browser's going psychotic?

I (very unusually!) "stooped to" HTML enabled mail to send e-mail to a
friend of a friend, the stupid thing then proceeds to change the To:
address from her address to the PICList - During sending this e-mail.

SORRY!

(Mike, why in the WORLD's the list letting HTML and images go through
the list, ideas?  It's bad enough Netscape's gone mad on this box, the
list shouldn't then allow it...  I sent it HTML-Only so was shocked to
see it re-post from the list, HTML and all...)

 Mark, disgusted - I think I'll go reboot now.

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2000\10\07@175220 by Mike

picon face
part 1 1142 bytes content-type:text/plain; charset=us-ascii (decoded quoted-printable)

Mark Willis wrote:
> (Mike, why in the WORLD's the list letting HTML and images go through
> the list, ideas?  It's bad enough Netscape's gone mad on this box, the
> list shouldn't then allow it...  I sent it HTML-Only so was shocked to
> see it re-post from the list, HTML and all...)

The HTML came through because of the way the server does the HTML stripping. The way it does this is it looks for a message that has *both* an HTML
attachment *and* a plain text attachment.  It then strips the HTML
attachment off.  It does this because that's the way that the "Rich Text"
messages *usually* come through.  But there's a few seriously brain damaged
email clients out there that sometimes do just an HTML attachment with no
plain text attachment.

As for the image - it came through because we never told the server not to.
-- Mike Werner  KA8YSD   | He that is slow to believe anything and
                     | everything is of great understanding,
'91 GS500E            | for belief in one false principle is the
Morgantown WV         | beginning of all unwisdom.



part 2 233 bytes content-type:application/pgp-signature (decode)

part 3 133 bytes
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2000\10\08@084858 by Oliver Broad

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face
> I (very unusually!) "stooped to" HTML enabled mail to send e-mail to a
> friend of a friend, the stupid thing then proceeds to change the To:
> address from her address to the PICList - During sending this e-mail.

And managed to give it a valid tag too, I thought at first you might have
been going for the 'most off topic post on PICLIST' world record?

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2000\10\08@132412 by Mark Willis

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face
Oliver Broad wrote:
> > I (very unusually!) "stooped to" HTML enabled mail to send e-mail to a
> > friend of a friend, the stupid thing then proceeds to change the To:
> > address from her address to the PICList - During sending this e-mail.
>
> And managed to give it a valid tag too, I thought at first you might have
> been going for the 'most off topic post on PICLIST' world record?

Nope, this brain-scrambled Browser did that, not me!  I'd be far more
creative if trying for that, and hardly would post from here <G>

The Subject line originally was "Re: Aha, you Are #### #######'s Friend!
<G>" (slightly anonymized with '#'s <G>) - Apparently some different
memory struct than I saw in the Mail Compose window was recycled, to
provide subject and address for the post.  I'm QUITE annoyed, that's not
playing fair.  Browsers are supposed to forewarn me, not "drygulch" me!

Perils of using a browser and not re-booting 3+ times a day, I guess <G>

 Mark

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'[OT]: Brain Burp Rounding??'
2001\05\30@115223 by Roman Black
flavicon
face
I was tabulating some data tonight, ie, doing
a division on my pocket calculator and then rounding
the number to three decimal places, then writing
the figure down on paper.

How do people round numbers to the nearest decimal
place on their pocket calculators?

My whole life I have checked if the last digit is
5, then if so check the next digit is 5, etc,
then once you get to a non-5 round it up or down.
Hope that makes sense.

So:
3.12471 = 3.125
3.12441 = 3.124
3.1245551 = 3.124
3.1245556 = 3.125

This just can't be right!
How were you taught? I started using pocket
calculators when they had led digits, probably
before I was 10 years old. I'm sure in school we
were taught to round digits like that. ??
-Roman

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2001\05\30@115901 by Alan B. Pearce

face picon face
>How do people round numbers to the nearest decimal
>place on their pocket calculators?

Easy, just set my TI-83 to 3 dec places. It keeps higher precision
internally if I need to change it. Yeah, I know, not quite what you wanted
to hear :)

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2001\05\30@120447 by Nick Taylor

flavicon
face
Roman Black wrote:
>
> I was tabulating some data tonight, ie, doing
> a division on my pocket calculator and then rounding
> the number to three decimal places, then writing
> the figure down on paper.
>
> How do people round numbers to the nearest decimal
> place on their pocket calculators?
On my calulator I round to three places by setting the display to only
show three places .... less brain strain.
{Quote hidden}

You're right, it's not right.  Just drop the digits past the third
decimal, then only consider the third decimal in your rounding.
>
> This just can't be right!
> How were you taught? I started using pocket
> calculators when they had led digits, probably
> before I was 10 years old. I'm sure in school we
> were taught to round digits like that. ??
> -Roman

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2001\05\30@121940 by David W. Gulley

flavicon
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Roman Black wrote:
{Quote hidden}

I have used the following:

 3.12350 = 3.124 (if exactly .xxx50000, round up if previous digit odd)
 3.12450 = 3.124 (if exactly .xxx50000, round down if previous digit
even)

The idea here is that if you are tallying a series of values, the
"random" nature of rounding some up, some down will "tend" to average
out the errors. (This is a very debatable subject!)


 3.12451 = 3.125 (greater than .xxx50 so round up)
 3.12449 = 3.124 (less than .xxx50 so round down)

following the previous two examples:
 3.1245000000001  = 3.125 (greater than .xxx50 so round up)
 3.1244999999999  = 3.124 (less than .xxx50 so round down)

for the examples you used:
3.1245551 = 3.125   (greater than .xxx50 so round up)
3.1245556 = 3.125   (greater than .xxx50 so round up)

David W. Gulley
Destiny Designs

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2001\05\30@122943 by eter William Green

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roman,

i was taught to round up if it's >= 1/2.  little different than you system - little easier

> 3.12471 = 3.125
> 3.12441 = 3.124
> 3.1245551 = 3.124
> 3.1245556 = 3.125

3.1247 = 3.125   7 >= 5 round up
3.1244 = 3.124   4 <  5 truncate
3.1245 = 3.125   5 >= 5 round up
3.1245 = 3.125   5 >= 5 round up

ie: i only check the 4th digit. if it's >= 5 round up.  if not truncate.

-pete



On Thu, 31 May 2001, Roman Black wrote:

{Quote hidden}

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2001\05\30@124335 by Cris Wilson

flavicon
face
At 01:48 AM 5/31/01 +1000, you wrote:
{Quote hidden}

I first look and see how many digits my answer needs to have. I then carry
one extra digit
than needed and just drop the other digits. Unless I have a function
involved (like sin, cos,
e, LN, pi, etc), I carry all digits for the number associated with the
function. When all of
the calculations are done I use that last extra digit to decide whether or
not to round up
the final answer. If the last digit is 5 or greater I round up the next digit.

Of course there are tons of books on precision, accuracy, and error
calculations if you
really want something set down in writing as a reference. ASTM I know has a
section
on proper significant figure use. Measurement theory textbooks usually
contain a chapter
on proper rounding as well.

_____________________________________________________________
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Clemson University
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2001\05\30@125600 by Kevin Blain

flavicon
face
Roman said.....

> How do people round numbers to the nearest decimal
> place on their pocket calculators?

and....

>
> So:
> 3.12471 = 3.125
> 3.12441 = 3.124
> 3.1245551 = 3.124
> 3.1245556 = 3.125
>
> This just can't be right!

It's not.

3.1245551 goes to 3.124 because it's greater than halfway (3.1425)

It's the old, add 5, 0.5, 0.05, etc, in your case, add 0.0005, and then
truncate it to n d.p.(in your case 3)

rule: add 5 x 10 exp -(decimal_places) then truncate to (decimal_places)
places.

That's almost how I was taught, but it's how I do it.

Regards, Kevin

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2001\05\30@130538 by Barry Gershenfeld

picon face
We were taught: "Round off to make even".  It sounded outrageous
then and I'll admit to not doing it that way much.  But I think
the reasoning is sound.  Other posters have already said so.
Paraphrasing the example:
3.12471 = ?
3.12441 = ?
3.1245551 = ?
3.1245556 = ?

Nick Taylor said:
>You're right, it's not right.  Just drop the digits past the third
>decimal, then only consider the third decimal in your rounding.

Thus, in each example you consider just 3.124   =:-o

The premise is that since you are rounding to 3 digits, that the
4th digit is not reliable anyway (even though it looks like it
should be!)  Then, as David Gulley said:

>The idea here is that if you are tallying a series of values,
> the "random" nature of rounding some up, some down will
> "tend" to average out the errors.

And so they divide all possible digits into two groups:
0,2,4,6,8  and 1,3,5,7,9  .  So if digits occur randomly
then 50% of the time you round up and 50% of the time
you don't.

And in the example the answer is 3.124 no matter what
follows.

3.124x = 3.124
3.124xxxx = 3.124    (even if the x's are 9's  =:-o)

3.125x -> 3.126
3.126x -> 3.126
3.127x -> 3.128
3.128x -> 3.128   et c.

Well, I went to school in New Jersey :)  You wanted to know
what we were taught.  Take it or leave it. :)

Barry

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2001\05\30@131341 by Bob Ammerman

picon face
I use "banker's rounding". This is also called "round to even" rounding.
When the digit being eliminated is a 5 you go up or down as needed to get to
an even number. Unlike conventional rounding (where you round up on 5 or
higher) banker's rounding does not have a slight positive bias in it.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)


{Original Message removed}

2001\05\30@131542 by Nick Taylor

flavicon
face
ooops!  I just read my post, and I didn't type what I meant to type.  I
should have said:  Just drop the digits past the fourth decimal, then
only consider the fourth decimal in your rounding.
 -N.

Nick Taylor wrote:
{Quote hidden}

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2001\05\30@133808 by Barry Gershenfeld

picon face
>ooops!  I just read my post, and I didn't type what I meant to type.  I
>should have said:  Just drop the digits past the fourth decimal, then
>only consider the fourth decimal in your rounding.
>  -N.

Yeah and it was just enough to convince me that my flawed
explanation was ok!  I thought something looked strange. So
I guess we did use that one digit past where you round to,
and then, as Bob just said, do the "make even" thing if
that digit is a 5.

Enough of this, I don't even use it...

Barry

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2001\05\30@160440 by Harold M Hallikainen

picon face
       If the digit beyond what you are rounding is higher than 5, round up,
lower than 5, round down. If equal to 5, round to the even digit. For
example,

3.4 rounds to 3
3.5 rounds to 4
3.6 rounds to 4

4.4 rounds to 4
4.5 rounds to 4
4.6 rounds to 5

       Using this "even digit" method (though an odd will also work), errors do
not accumulate as multiple random rounded numbers are added.

Harold


On Thu, 31 May 2001 01:48:00 +1000 Roman Black <fastvidspam_OUTspamEZY.NET.AU>
writes:
{Quote hidden}

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2001\05\30@203042 by Alexandre Domingos F. Souza

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>How do people round numbers to the nearest decimal
>place on their pocket calculators?

       HP people have the Round(F) function.

>How were you taught? I started using pocket
>calculators when they had led digits, probably
>before I was 10 years old. I'm sure in school we
>were taught to round digits like that. ??

       Mee too.

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2001\05\30@203244 by michael brown

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face
> roman,
>
> i was taught to round up if it's >= 1/2.  little different than you
system - little easier
{Quote hidden}

Finally some one got it right!  ;-D  Way to go Pete.  If you want to round
to N decimal places then look at position N+1.  If position (N+1) >4 then
increment position(N).  That's all there is to it.  You don't have to look
at anything else.   Hope this helps.  TTYL

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2001\05\31@014757 by Dale Botkin

flavicon
face
On Wed, 30 May 2001, Peter William Green wrote:

> roman,
>
> i was taught to round up if it's >= 1/2.  little different than you system - little easier
>
> > 3.12471 = 3.125
> > 3.12441 = 3.124
> > 3.1245551 = 3.124
> > 3.1245556 = 3.125
>
> 3.1247 = 3.125   7 >= 5 round up
> 3.1244 = 3.124   4 <  5 truncate
> 3.1245 = 3.125   5 >= 5 round up
> 3.1245 = 3.125   5 >= 5 round up
>
> ie: i only check the 4th digit. if it's >= 5 round up.  if not truncate.
>
> -pete

Yup, we were taught that as "artillery roundoff" in the Army.  Carry it
out as many digits as you want...

3.124555551 = 3.125
3.124555556 = 3.125

Dale
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2001\05\31@053859 by Roman Black

flavicon
face
Hi Michael, yep, darn right, half the people in
the world (including me!) have been rounding wrongly
their entire lives. Very scary. There is and can only
be one correct way of rounding decimal numbers...

Here is an example, assuming rounding to 3 decimal
places, that is 1000 combinations, from 000 to 999.

000 to 499 (first half), 500 to 999 (second half).
There are the first 500 combinations in the first
half, and the second 500 combination in the second
half.

All my life I have been rounding at 555, under the
false impression that 5 is "half way" in decimal
terms... Wow.

I asked my 26 yr old science-degreed girlfriend how
to round and she looked at me like I was stupid.
"5 or more, round up". She was taught correctly.

Now I'm wondering if it is mainly us old-timers
from the dawn of pocket calculators age that were
taught wrong?? Any thoughts, older people??
:o)
-Roman


michael brown wrote:
{Quote hidden}

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2001\05\31@083724 by michael brown

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I'm pretty old myself (39), but I have seen calculators that have something
called 5/4 rounding.  Being uneducated (no degree) I'm not sure what that is
about.  Remember the good ole RPN calculators?  If you could understand how
to use one of those, you were well on your way to being a FORTH programmer.

Michael Brown
Instant Net Solutions
http://www.KillerPCs.net




{Quote hidden}

truncate.
> > >
> > > -pete
> >
> > Finally some one got it right!  ;-D  Way to go Pete.  If you want to
round
> > to N decimal places then look at position N+1.  If position (N+1) >4
then
> > increment position(N).  That's all there is to it.  You don't have to
look
> > at anything else.   Hope this helps.  TTYL
>
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2001\05\31@102928 by David W. Gulley

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Roman Black wrote:
{Quote hidden}

Cept for one minor detail,

There are 999 values BETWEEN 0 and 1000.
  500 IS the halfway point.
    500 values below it (0 - 499) and
    500 values above it (501 - 1000).
Therefore, if accumulating a large series of "random" numbers and
rounding using the 5 or greater rule, the result will "tend" to be too
large since statistically you are using 500 possibilities below the
number and 499 above the number.

For most things this error would probably not be a problem, but the
"round to even if 5" rule will "tend" to average out the error
accumulation at the expense of complicating the rule slightly.

The validity of the least significant digits does play an important role
in the process, so when absolute accuracy is required use a tolerance
(+/-) to exactly specify the values, and the error accumulation.
 For example (round to nearest 1/100):
   Value   Tolerance    Round >=5     Round to Even if 5
   1.125   +/- 0.005      1.13          1.12
   1.135   +/- 0.005      1.14          1.14
    Repeat above 1000 times and Total
   2260                   2270          2260

when the tolerances say:
   2260 +/- 10 or somewhere in the range of 2250 to 2270 so yes the
"Round >=5" is a 'correct' answer (since it is in the possible range
defined by the tolerances, even if it is at the upper limit), but the
2260 provided by the "Round to even if 5" is a 'better' answer (in some
cases).

 Obviously this is a contrived scenerio, but if a particular sensor
reported to 0.5 units of precision with +/- 0.5 units of accuracy, and
you wanted to accumulate readings over a long interval, the "Round >=5"
will provide an answer that is "typically" too large.

If you were buying gasoline, and the pumps all rounded using the "Round
>=5" rule, would you mind that you were charged for 2270 gallons instead of 2260? :-)

As I stated in an earlier message in this thread,
   This is a very debatable subject!


David W. Gulley
Destiny Designs

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2001\05\31@103822 by Harold M Hallikainen

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       Good o' RPN calculators!  I still have my HP35 from 1972 and use an
HP15C (I think that's the number) daily. I still agree with the old T
shirts that [ENTER] > = .
       I teach electronics at night at the local community college. My students
all have very fancy calculators that use algebraic notation. And they
consistently get the wrong answer. They're always leaving out parenthesis
and having the calculator solve a problem other than the one they want.
RPN solves this by having you work the problem the way you would by hand:
from the inside out. Also, you see all intermediate results so you can
catch errors if you have a feel for the numbers.
       On rounding, here's an example:

1.5+2.5 = 4.0 without rounding

With rounding using "round to even"

2 + 2 = 4

With "rounding up"

2 + 3 = 5

Round to even tends to minimize error.

Harold


On Thu, 31 May 2001 07:31:01 -0500 michael brown <@spam@n5qmgSTOPspamspam@spam@AMSAT.ORG>
writes:
{Quote hidden}

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2001\05\31@110645 by Kevin Blain

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NO! becasue 1000 is the same as 0. Er - that needs explaining! i.e. there
are 500 numbers 0-499 inclusive and 500 numbers 500-999 inclusive. So the
1000 is the 0 in the next set.

Regards, Kevin


{Original Message removed}

2001\05\31@111700 by Patrik Husfloen

picon face
I only used an RPN calc for a few days but I got hooked imediatly,
those things are great, think I used an HP 32 II or something like that.
I normally use an TI83 though. I like the RPN calc much better.

{Original Message removed}

2001\05\31@113549 by David W. Gulley

flavicon
face
To say "NO!" is a bit emphatic, since I could just as well say that we
will only truncate numbers, which would provide an answer which may be
fine for some conditions.

I understand your logic; but this is still including 500 numbers below
the "rounded to" value and 499 above, therefore (and I repeat)
statistically, you are favoring the round up when given a random set of
values.

 Again looking at the results of the scenario I presented below,
The actual answer is                 2260 +/- 10

The "Round >=5" result is            2270  (+0/-20)
The "Round Even if 5" result is      2260  (+/- 10)
And the "Truncate" result is         2250  (+20/-0)

So which answer is right?
  All of them (or none of them) depending on the requirements...

David W. Gulley
Destiny Designs


Kevin Brain wrote:
>
> NO! becasue 1000 is the same as 0. Er - that needs explaining! i.e. there
> are 500 numbers 0-499 inclusive and 500 numbers 500-999 inclusive. So the
> 1000 is the 0 in the next set.
>
> Regards, Kevin
>
> {Original Message removed}

2001\05\31@113952 by Bill Westfield

face picon face
   Now I'm wondering if it is mainly us old-timers
   from the dawn of pocket calculators age that were
   taught wrong?? Any thoughts, older people??

Hmm.  I'm 41, learned to use a slide rule in high school, and learned "5 or
more; round up" (and also "add .5 and truncate", on ASR33.)  Actually,
number lines were very popular in the "new math" cirricula, and it was/is
awfully clear that EXACTLY halfway is the only sticky point.  I'd never
heard of the odd/even rounding mentioned here before, but that makes sense.

BillW

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2001\05\31@114618 by Bob Barr

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Roman Black <TakeThisOuTfastvidspamspamRemoveMEEZY.NET.AU> wrote:

<snip>

{Quote hidden}

Early Bronze Age recollections:

I was taught to go just one decimal beyond the digit to be rounded. Four or
less rounds down, 5 or more rounds up.

We were specifically taught that it doesn't matter what's beyond that first
digit. Whether the digit being rounded is odd or even was never mentioned as
being significant.


Bob
_________________________________________________________________
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2001\05\31@122418 by Kevin Blain

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000-499 round down
500-599 round up
1000-1499 round down
1500-1999 round up

etc. etc.

where is the uneven bias? where is the 'favouring rounding up?'

if you consider 1000 to be part of the 500-999 group (i.e. 0-4999 and
500-1000) then you are including the same number twice.

the scale is 0-9 in decimal, not 0-10

here's a scale

0,1,2,3,4   |  5,6,7,8,9

the | has an equal number of numbers on each side. The | does not go through
the number 5, it IMMEDIATLY precedes it, so if the scale had decimals in
too....

0.0 through 4.9 | 5.0 through 9.9

again, exactly the same number of numbers. The bar is infinately thin, and
therefore once the data is quantised, there is no possibility of the data
landing on the bar.

Regards, Kevin



{Original Message removed}

2001\05\31@122429 by Paul Hutchinson

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>Hmm.  I'm 41, learned to use a slide rule in high school, and learned "5 or
>more; round up"

Me too, on all three items :-).

However, when I got to chemistry class the teacher took extra care to teach
us the slightly more accurate way of rounding (odd/even).

Found this nice web tutorial on significant figures and rounding by, Stephen
L. Morgan, Professor, Department of Chemistry & Biochemistry, The University
of South Carolina.
http://www.chem.sc.edu/faculty/morgan/sigfigs/index.html


Paul

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2001\05\31@122840 by Roman Black

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David W. Gulley wrote:
{Quote hidden}

No, actually 4.99999999999 (repeating) is the
half-way point.
5.0 is definitely in the top half.
Decimal has ten digits, 0-4 are the bottom 5 and
5-9 are the top 5. Anything under 500 is the
bottom half, and anything from 5.0 up is the
top half. Nothing debatable about it, just like
0-127 is the bottom half and 128-255 are the
top half in binary. :o)
-Roman

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2001\05\31@123502 by Roman Black

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David W. Gulley wrote:
>
> To say "NO!" is a bit emphatic, since I could just as well say that we
> will only truncate numbers, which would provide an answer which may be
> fine for some conditions.
>
> I understand your logic; but this is still including 500 numbers below
> the "rounded to" value and 499 above, therefore (and I repeat)
> statistically, you are favoring the round up when given a random set of
> values.


I don't understand your logic?? There are 500 values,
ie, 000 to 499, then there are 500 values in the top
half, ie, 500 to 999. The dividing point is *immediately*
before 500, ie, 499.999999999999999 (forever)

So if it starts with a 5 it absolutely must be in the
top half. There is no favoring, just accuracy.
-Roman

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2001\05\31@124342 by Doug Joel

picon face
Does this really have anything to do with statistics?

I thought it was representing a more accurate number with
fewer digits.

Doug

{Original Message removed}

2001\05\31@133343 by Paul Hutchinson

flavicon
face
>No, actually 4.99999999999 (repeating) is the half-way point.
>5.0 is definitely in the top half.

4.99999999999 (repeating) = 5.00000000 (repeating)
Remember, repeating decimals are equal to an integer divided by 9.
1/9 = 0.1(repeating)
2/9 = 0.2(repeating)
3/9 = 0.3(repeating) = 1/3
4/9 = 0.4(repeating)
5/9 = 0.2(repeating)
6/9 = 0.6(repeating) = 2/3
7/9 = 0.7(repeating)
8/9 = 0.8(repeating)
9/9 = 0.9(repeating) = 1


Maybe this example will help illustrate the bias in >=5 rounding versus
odd/even rounding.

You have four numbers to sum, 1.5, 2.5, 3.5, 4.5
Using the decimal values:
1.5 + 2.5 + 3.5 + 4.5 = 12.

If we round using >=5 rounding:
2 + 3 + 4 + 5 = 14

If we round using odd/even rounding:
2 + 2 + 4 + 4 = 12

Is it any wonder that on Massachusetts State Income Taxes you must (by law)
use the >=5 rounding method, more revenue for the state :-).
Actually, because you use the same rounding for exemptions/deductions as for
income the revenue isn't any better for the state but, the simpler >=5
rounding is easier on the tax preparer.

BTW - The CINT() rounding function in all flavors of Microsoft Basic
languages uses odd/even rounding.

Paul

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Chief Engineer
Maximum Inc., 30 Samuel Barnet Blvd.
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2001\05\31@140430 by Roman Black

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Paul Hutchinson wrote:

> Maybe this example will help illustrate the bias in >=5 rounding versus
> odd/even rounding.
>
> You have four numbers to sum, 1.5, 2.5, 3.5, 4.5
> Using the decimal values:
> 1.5 + 2.5 + 3.5 + 4.5 = 12.
>
> If we round using >=5 rounding:
> 2 + 3 + 4 + 5 = 14


This is what I would expect. The numbers x.5 are
all on the TOP half of the decimal spread, so of
course the average or total of them will be greater
than the half way mark. 0.00 to 0.49 is in the first
half, 0.50 to 0.99 is in the second half.
Just like 0 to 127 is the first half and 128 to 255
is the second half in binary.

Where you might be confused is that 0.50 is not
the half way point between 0 and 1. The half way
point is AFTER 0.4999999 and BEFORE 0.5.
So 0.5 is past the half way mark.

:o)
-Roman

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2001\05\31@163350 by Paul Hutchinson

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>This is what I would expect. The numbers x.5 are
>all on the TOP half of the decimal spread, so of
>course the average or total of them will be greater
>than the half way mark. 0.00 to 0.49 is in the first
>half, 0.50 to 0.99 is in the second half.
>Just like 0 to 127 is the first half and 128 to 255
>is the second half in binary.
>
>Where you might be confused is that 0.50 is not
>the half way point between 0 and 1. The half way
>point is AFTER 0.4999999 and BEFORE 0.5.
>So 0.5 is past the half way mark.

Absolutely not true!

I think I see where the confusion is occurring. You are talking about
numbers limited to ranges of 2^x-1 (computer representations of numbers). In
the first paragraph you are talking about a range of 0.00 -> 0.99 (not
1.00).
In the second paragraph you change the range to 0 -> 1 but don't take into
account the change.

The mid way point of any range of numbers is exactly equal to:
(highest value - lowest value) / 2 + lowest value.

For the normal one byte range (0->255) this is:
(255 - 0) / 2 + 0 = 127.5

For the range of 0.00->0.99 it's:
(0.99 - 0.00) / 2 + 0.00 = 0.495

For the range of 0->1 it's:
(1 - 0) / 2 + 0 = 0.5

Here's all the possible 1 decimal place numbers in the range of 0 to 1.
They are: 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and, 1.0.

There are 11 values and 0.5 is exactly the half way point of a 0 to 1
sequence. There are five numbers above and, five numbers below the mid way
point.

Paul

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2001\05\31@173739 by Bill Westfield

face picon face
   I don't understand your logic?? There are 500 values,
   ie, 000 to 499, then there are 500 values in the top
   half, ie, 500 to 999. The dividing point is *immediately*
   before 500, ie, 499.999999999999999 (forever)

   So if it starts with a 5 it absolutely must be in the
   top half. There is no favoring, just accuracy.

No, because we're not talking about "number of values" when rounding, we're
talking about a "distance."  There are (always) an infinite number of values
between any two numbers, but .5 is exactly half-way between 0 and 1, so
going consistantly either up or down introduces a slight bias.

Or, looking at all the values of precision N+1 that round to a particular
value, you'll find that there are 5 values that round up to that value, and
only 4 values that round down to it (plus the value itself.)

A trivial pieces of software ought to be able to calculate the accumulated
error over a large number of samples, which IS the value you want to
minimize.  Right?

BillW

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'[OT]: Brain Burp Rounding??'
2001\06\01@051140 by Roman Black
flavicon
face
William Chops Westfield wrote:
>
>     I don't understand your logic?? There are 500 values,
>     ie, 000 to 499, then there are 500 values in the top
>     half, ie, 500 to 999. The dividing point is *immediately*
>     before 500, ie, 499.999999999999999 (forever)
>
>     So if it starts with a 5 it absolutely must be in the
>     top half. There is no favoring, just accuracy.
>
> No, because we're not talking about "number of values" when rounding, we're
> talking about a "distance."  There are (always) an infinite number of values
> between any two numbers, but .5 is exactly half-way between 0 and 1, so
> going consistantly either up or down introduces a slight bias.


Alright, so you are saying it looks more like
this:

0 to 499 = bottom half (500 units)
500 = dead centre
501 to 999 = top half. (499 units)

This still makes no sense to me. You have a very
obvious bias, one half is bigger than the other.
We are not working with distances, instead there
are a very finite number of possible combinations
in our 3 digits. 0 to 999. There are 1000 total
possible numerical combinations.

1000 can't be included as it is the first combination
of the next 1000 units. And 2000 is the first of the
next block after that.

If you don't believe me write a program that generates
a 3-digit random number and then round it... 500 is
past half way and must be rounded up. :o)
-Roman

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2001\06\01@063639 by Bob Ammerman

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Roman,

This 'distance' thing really is the way to look at it.

Since n+0.500 is right in the middle between 'n' and 'n+1', the error
introduced is equal (but of opposite sign), whether you go down to 'n' or up
to 'n+1'. So, to have a statistically average error of zero you just go up
half the time and down half the time (ie: round to even).

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)



{Original Message removed}

2001\06\01@064942 by Kevin Blain

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No it doesn't because 9/9 == 1, not 0.9(recurring) (and 5/9 is not 0.2
recurring, but I guess that was a typo!)

4.99999999999 (repeating) is not equal to 5.00000000 (repeating), that's why
we have different numbers to express it. However, 4.99999999999 (repeating)
is nearly equal to 5

This reminds me of the thing where :-

- There is 1 cake
- Each person takes half of the amount of cake that is left, indefinatly

Therefore there is always some cake left......

Regards, Kevin



{Quote hidden}

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2001\06\01@070637 by Kevin Blain

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face
but n+1 is in the next set. the range should be from n to
n+0.999999999999(recurring)

example.

Here are 10 numbers ( fairly equally distributed between 0 and 1, i.e they
are not biased toward either end) , round them to the nearet integer, then
take the average. Also take the average of the numbers - they should be the
same if the rounding method works


0.05  0.15  0.25  0.35  0.45  0.55  0.65  0.75  0.85  0.95

rounded intergers are: 0  0  0  0  0  1  1  1  1  1 (my method)
average of integers is 0.5

average of actual numbers is 0.5

Regards, Kevin



{Original Message removed}

2001\06\01@070653 by Alan B. Pearce

face picon face
My brain burps from all this rounding... It just seems to go round and round
and round and round.... are we having fun yet? that would make it a merry go
round :)

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2001\06\01@072306 by michael brown

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face
> Is it any wonder that on Massachusetts State Income Taxes you must (by
law)
> use the >=5 rounding method, more revenue for the state :-).
> Actually, because you use the same rounding for exemptions/deductions as
for
> income the revenue isn't any better for the state but, the simpler >=5
> rounding is easier on the tax preparer.

I was wondering when this was going to be brought up.  I can only imagine
trying to explain to the IRS at an audit that you were only rounding the
"other" way in the interest of national accuracy.  BTW if accuracy is so
important that even/odd rounding is needed, then the (IMHO) sensible way to
deal with the math is to carry more digits of precision than required and
then (and only then) round the final total.  IIRC (its been a long time)
this is the way the COBOL compiler did math, I suspect other compilers do
the same.

michael

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2001\06\01@082303 by Thomas McGahee

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face
Sorry, but .99999 repeating is EXACTLY equal to 1.00000

They are just two different ways of EXPRESSING the same
number. Don't believe me? 1/9=.11111 repeating. 2/9=.22222 repeating.
3/9=.3333333 repeating. 4/9=.4444 repeating, 5/9=.55555 repeating.
6/9=.6666 repeating. 7/9=.7777 repeating. 8/8=.888 repeating.
So 9/9=.99999 repeating. The "error" between .999 repeating and
1.000 (repeating, by the way!) is .0000 repeating. Get it?

.999 repeating and 1.000 (repeating the 000 part) are simply two
different ways of EXPRESSING the value. They may LOOK different,
but mathematically the difference is ZERO.

.999 repeating, 9/9, x/x (where x is non-zero), 1,  1.000 repeating
all REPRESENT the same VALUE. One.

Fr. Tom McGahee

{Original Message removed}

2001\06\01@092542 by Paul Hutchinson

flavicon
face
>No it doesn't because 9/9 == 1, not 0.9(recurring)

You missed the point, I was saying that 0.9(repeating) is absolutely equal
to 1. This is a basic principal of mathematics that I think was taught to me
in junior high school.

Here is the algebraic proof:

Given:
 x = 0.9(repeating)
Multiply both sides by 10:
 10x = 9.9(repeating)
Subtract x from both sides:
 10x - x = 9.9(repeating) - x
Substitute value for x on right side:
 10x - x = 9.9(repeating) - 0.9(repeating)
Simplify right side:
 10x - x = 9
Simplify left side:
 9x = 9
Divide both sides by 9:
 x = 1
Substitute value for x on left side:
0.9(repeating) = 1


>(and 5/9 is not 0.2 recurring, but I guess that was a typo!)

Yep, a typo should have been 0.5(repeating)

>4.99999999999 (repeating) is not equal to 5.00000000 (repeating), that's
why
>we have different numbers to express it. However, 4.99999999999 (repeating)
>is nearly equal to 5

As above 4.99999999999 (repeating) is exactly equal to 5.

Paul

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2001\06\01@093431 by Alan B. Pearce

face picon face
>Given:
>  x = 0.9(repeating)
>Multiply both sides by 10:
>  10x = 9.9(repeating)
>Subtract x from both sides:

The fallacy in this argument is that at the end x->1, as any repeating
number is not exact.

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2001\06\01@110639 by Roman Black

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face
Alan B. Pearce wrote:
>
> My brain burps from all this rounding... It just seems to go round and round
> and round and round.... are we having fun yet? that would make it a merry go
> round:)


Ha ha!!! That has got to be a 3 bourbon answer if I
ever heard one. I am feeling the same way. I never
thought rounding a simple decimal number would spark so
much controversy...
:o)
-Roman

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2001\06\01@112711 by Doug Joel

picon face
The there is .00001 difference between .99999 and
1.00000....



----- Original Message -----
From: Thomas McGahee <tom_mcgaheeKILLspamspamEraseMESIGMAIS.COM>
To: <EraseMEPICLIST@spam@spam@spam@MITVMA.MIT.EDU>
Sent: Friday, June 01, 2001 5:24 AM
Subject: Re: [OT]: Brain Burp Rounding??


> Sorry, but .99999 repeating is EXACTLY equal to 1.00000
>
> They are just two different ways of EXPRESSING the same
> number. Don't believe me? 1/9=.11111 repeating. 2/9=.22222
repeating.
> 3/9=.3333333 repeating. 4/9=.4444 repeating, 5/9=.55555
repeating.
> 6/9=.6666 repeating. 7/9=.7777 repeating. 8/8=.888
repeating.
> So 9/9=.99999 repeating. The "error" between .999
repeating and
> 1.000 (repeating, by the way!) is .0000 repeating. Get it?
>
> .999 repeating and 1.000 (repeating the 000 part) are
simply two
> different ways of EXPRESSING the value. They may LOOK
different,
> but mathematically the difference is ZERO.
>
> .999 repeating, 9/9, x/x (where x is non-zero), 1,  1.000
repeating
{Quote hidden}

5/9 is not 0.2
> > recurring, but I guess that was a typo!)
> >
> > 4.99999999999 (repeating) is not equal to 5.00000000
(repeating), that's
> why
> > we have different numbers to express it. However,
4.99999999999
> (repeating)
> > is nearly equal to 5
> >
> > This reminds me of the thing where :-
> >
> > - There is 1 cake
> > - Each person takes half of the amount of cake that is
left, indefinatly
> >
> > Therefore there is always some cake left......
> >
> > Regards, Kevin
> >
> >
> >
> > > 4.99999999999 (repeating) = 5.00000000 (repeating)
> > > Remember, repeating decimals are equal to an integer
divided by 9.
{Quote hidden}

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> >
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2001\06\01@114644 by Roman Black

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OK, so now I feel totally inadequate to do rounding
in my simple data table.

As everyone seems to have their own system for rounding
I would like to ask a simple question andd hopefully one
of the math geniuses can give a simple answer??

I do a divide calc (on pocket calculator) that gives a
0.xxxxx answer. I need to round this and make it a binary
number (to fit in one byte).

So 0.400 x 256 = 102.4 = 102 (binary).

Any suggestions for rounding these data figures??
:o)
-Roman

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2001\06\01@114846 by Bob Barr

picon face
Kevin Blain <RemoveMEkevinbKILLspamspamRemoveMEWOODANDDOUGLAS.CO.UK> wrote:

>Subject: Re: [OT]: Brain Burp Rounding??
>Date: Fri, 1 Jun 2001 11:44:44 +0100
>

<snip>

>
>This reminds me of the thing where :-
>
>- There is 1 cake
>- Each person takes half of the amount of cake that is left, indefinatly
>
>Therefore there is always some cake left......
>

A similar story is told of a mathematician and an engineer presented with a
problem concerning a beautiful woman located 10 feet away. Each is told that
he can halve the distance to her every 10 minutes and asked how long it will
be until he reaches her.

The mathematician states that he will never be able to reach her.

The engineer figures that, within the hour, it'll be close enough for him.
:=)

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com

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2001\06\01@115058 by Dipperstein, Michael

face picon face
> From: Alan B. Pearce [TakeThisOuTA.B.PearcespamRL.AC.UK]
>
> >Given:
> >  x = 0.9(repeating)
> >Multiply both sides by 10:
> >  10x = 9.9(repeating)
> >Subtract x from both sides:
>
> The fallacy in this argument is that at the end x->1, as any repeating
> number is not exact.

I don't understand where the fallacy lies.  A repeating number *is* exact as
long as it isn't truncated.

1/3 is exactly .3 (repeating)

1/3 is not exactly .3333333 or .3333333333 or any truncated version.

Along that line here's another simple Junior High School algebra proof that 1 =
.9 repeating.

1/3 = .3 repeating

multiply both sides by 3

(1/3)*3 = 3 * (.3 repeating)

1 = .9 repeating

-Mike

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2001\06\01@121653 by Paul Hutchinson

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> The fallacy in this argument is that at the end x->1, as any repeating
> number is not exact.

Wrong, all repeating fractions have an exact representation (they are
rational numbers). Only irrational numbers like PI have no exact
representation.

<rant on>
I consider, a complete understanding of rounding and number systems (very
basic algebra) to be absolutely essential for good engineering. In my
opinion, anyone involved in engineering of any sort should understand basic
algebra completely. Now, I'm not saying that all engineers must have this
info memorized but, they must have a gut feel for it and know where to look
up the precise info (e.g. their old text books).
<rant off>

In an attempt to help members learn the basics of algebra I searched the web
for some good references. However most of what I found was written for
children 13 years and younger (the authors expect the student to accept some
math principals on faith and, we all know that good engineers never accept
anything on faith :-).

I did find that James Brennan, professor of physics and mathematics at Boise
State University in the College of Applied Technology, has posted the
complete contents of his book "Understanding Algebra" online at:
http://www.edteach.com/algebra/
Read the "Decimals" section of Chapter 1 for info on rounding.
BTW - the subject of repeating fractions is also covered in that section.

For those who may have missed it the first time I posted it, here's a nice
web tutorial on significant figures and rounding by, Stephen
L. Morgan, Professor, Department of Chemistry & Biochemistry, The University
of South Carolina.
http://www.chem.sc.edu/faculty/morgan/sigfigs/index.html

Paul

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2001\06\01@122822 by Wendy J Olend

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It seems that we have broken into two camps, the "Always Round Up-ers"
(ARU)  and the "Round to Even Crew" (REC).  Being a member of the latter
camp, I'm going to try my hand at explaining our stance.

I've been watching everyone go back and forth, arguing if 5 is the
mid-point between 0 and 9 (REC) or if it's part of the upper half of the
set (ARU).  Of course it is part of the upper half of the set
{0,1,2,3,4,5,6,7,8,9}.  The confusion comes in at this point:  The
round-to-even method is meant to minimize rounding error.  When 0 is the
digit under consideration, there IS no rounding error introduced.  Before
the flames head my way, let me elaborate.

We all agree on this point:  when you decide to round a number you first
decide how many digits you want in the final answer, then you throw away
all but one plus that number of digits:

Example:   13.1032
If I decide that I want to report my answer with only one decimal place.  I
truncate, leaving 13.10  Now we have to ask, "What does this value mean?"
Putting this value into words, it means "I have exactly 13.1, and it what
appears to be 0 in the hundredths place."  When I "round" this number to
13.1, I have not introduced any further error, merely reduced the
precision.

Example:   13.1132 to the tenths place, I start with 13.11, which means "I
have exactly 13.1, and what appears to be 1 in the hundredths place."  When
I truncate this value, I have reported the value as less than I have
observed it to be.  Hence the "rounding error".  The same happens when you
round up.

Looking at the error inducing numbers: {1,2,3,4,5,6,7,8,9}, it becomes
obvious why we call 5 the mid-point of this set.  If we always round up at
five, we are putting a positive biasing on the data, because we are
rounding up more than half of the time.

The confusion occurs because for 0-4 it looks like you are doing the same
operation; truncation.  But for 0, you are actually just recasting the
value at a lower precision.

There's my $.02 worth,
Wendy

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2001\06\01@125249 by Alan B. Pearce

face picon face
>1 = .9 repeating

Except that the error is 0.0_repeating_1.

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2001\06\01@131046 by John Pfaff

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> >1 = .9 repeating
>
> Except that the error is 0.0_repeating_1.
which is exactly equal to zero.

For those who may have missed it:

1/9 = 0.111(repeating)
2/9 = 0.222(repeating)
...
8/9 = 0.888(repeating)
9/9 = 0.999(repeating) which is EXACTLY EQUAL TO ONE.

A math teacher explained this to me years ago (no Chris, not Mr. Zurick).

Also, I'm in the Round To Even crowd.  This method was explained in a college chemistry text and was to be used because it
statistically caused the least errors.

jp

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2001\06\01@132950 by Paul Hutchinson

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You got the rounding correct, by anyone's method :-).

But, if the input value can be > 0.99804 it will overflow the 8 bits.

To make it work for any value < 1 you should multiply by 255.

Paul

{Quote hidden}

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2001\06\01@170404 by Bill Westfield

face picon face
   <rant on>
   I consider, a complete understanding of rounding and number systems
   (very basic algebra) to be absolutely essential for good engineering. In
   my opinion, anyone involved in engineering of any sort should understand
   basic algebra completely. Now, I'm not saying that all engineers must
   have this info memorized but, they must have a gut feel for it and know
   where to look up the precise info (e.g. their old text books).
   <rant off>

To tie things in with previous discussions, I suspect that this sort of
thing is one of the differences between "degreed" engineers and "self
taught" engineers.  While repeating decimals are theoretically high-school
or earlier math, the sort of "gut feel" for non-intuitive values of limits
and such might be something that one gets drummed into them during the two
years of calculus and physics one endures as "perparation" to using Smith
charts and phasors for EE (not to mention that numerical analysis class.)

There'd be exceptions, of course.

OTOH, in software engineering, I've been rather shocked at how seldom
floating point ("real" numbers) actually gets used...

Is there a simple algorithm for doing the odd/even rounding (equivilent to
N+0.5 and truncate?)

(of course, we're now in big arguments over fine points.  Whether you
always round .5 up, or do te even/odd thing, your error introduced over
typical sample sizes is going to be pretty small.)

BillW

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2001\06\01@191009 by Andrew Warren

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William Chops Westfield <spamBeGonebillwKILLspamspamTakeThisOuTcisco.com> wrote:

> Is there a simple algorithm for doing the odd/even rounding
> (equivilent to N+0.5 and truncate?)

Bill:

There's a simple implementation in PIC assembly:

   ; Enter with integer in REG, fraction in the Carry flag.

       BNC     DONE    ;If the carry's clear, no rounding
                       ;is required, so jump.

       BTFSS   REG,0   ;If the integer is odd, skip ahead.
       INCF    REG     ;Otherwise, round up (i.e., round
                       ;to odd).

   DONE:

This implementation uses "round to odd" rather than "round to even"
in order to make the rounding of multi-byte integers easier; with
this method, only the least-significant byte is ever changed.

This introduces a tiny bit of bias, however, since only ONE value
(0.0) rounds to 0 while THREE values (254.5, 255.0, and 255.5) round
to 255.

If it were important for numbers close to 0 to round down to 0, you
could reverse things so that the bias was toward 0 rather than 255...
But then you'd non-intuitively be rounding 1.0 to 0.

-Andy


=== Andrew Warren --- EraseMEaiw.....spamKILLspamcypress.com
=== IPD Systems Engineering, CYSD
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

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2001\06\01@193126 by Alexandre Domingos F. Souza

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>I only used an RPN calc for a few days but I got hooked imediatly,
>those things are great, think I used an HP 32 II or something like that.
>I normally use an TI83 though. I like the RPN calc much better.

       I never liked RPN calculators. Had a HP20 and it was algebraic. Xchanged for a HP48G and it is RPN. Completely crazy, but once you got used to, you start to search for the "enter" key on other calculators :o)

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2001\06\01@201618 by Paul Hutchinson

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> To tie things in with previous discussions, I suspect that this sort of
> thing is one of the differences between "degreed" engineers and "self
> taught" engineers.  While repeating decimals are theoretically high-school
> or earlier math, the sort of "gut feel" for non-intuitive values of limits
> and such might be something that one gets drummed into them during the two
> years of calculus and physics one endures as "perparation" to using Smith
> charts and phasors for EE (not to mention that numerical analysis class.)
>
> There'd be exceptions, of course.

I guess, I'm an exception. I don't personally know any other self taught
engineers so I can't say how it stacks up but, my gut instinct is that you
are right Bill. I do know two degreed engineers who don't have a good feel
for mathematics, both close personal friends, and they both got out of
design engineering (one does engineering project management and the other
cranks out asp web code).

Paul

=========================================
Paul Hutchinson
Chief Engineer
Maximum Inc., 30 Samuel Barnet Blvd.
New Bedford, MA 02745
spamphutchinsonspamimtra.com
http://www.maximum-inc.com
=========================================

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2001\06\01@225753 by Kyle Stemen

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One thing I don't like about the round to even method is that you lose
precision. Say you are measuring a value from 0 to 9. You have one sig
fig, and 10 different possiblities of what that number can be. Now lets
say that you had to do a calculation such as add .5. You would have to
round back to one digit. Here are the different possiblities with round
to even:
0.5 -> 0
1.5 -> 2
2.5 -> 2
3.5 -> 4
4.5 -> 4
5.5 -> 6
6.5 -> 6
7.5 -> 8
8.5 -> 8
9.5 -> 10

with always round up you have

0.5 -> 1
1.5 -> 2
2.5 -> 3
3.5 -> 4
4.5 -> 5
5.5 -> 6
6.5 -> 7
7.5 -> 8
8.5 -> 9
9.5 -> 10

With the round to even you can only have an even number so there are 6
possibilites of what it can be, and you started out with 10 so you have
lost precision. With always round up there are still 10 possibilies so
you have lost no precision, but they do not average out the same so you
have lost accuracy.

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2001\06\02@053746 by Roman Black

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Paul Hutchinson wrote:

{Quote hidden}

Thanks Paul, you are absolutely right and I stand
humbled. I should indeed have a thorough understanding
of this.

Unfortunately the last time I sat in a classroom
doing calculus was over 15 years ago, and the amount
of times over the years I have actually needed formula
more intense than the usual freq/reactance etc stuff
has been pretty minimal.

Thanks for the nice links, I will check them out
this weekend. :o)
-Roman

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2001\06\02@055045 by Roman Black

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Bob Barr wrote:

> A similar story is told of a mathematician and an engineer presented with a
> problem concerning a beautiful woman located 10 feet away. Each is told that
> he can halve the distance to her every 10 minutes and asked how long it will
> be until he reaches her.
>
> The mathematician states that he will never be able to reach her.
>
> The engineer figures that, within the hour, it'll be close enough for him.
>:=)


Ha ha ha!! <cheeky> Hey, for some of us, 30 minutes
would be close enough... Think about it. ;o)
</cheeky>
-Roman

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2001\06\02@074137 by David W. Gulley

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Kyle Stemen wrote:
{Quote hidden}

Actually, you lose no precision or accuracy, if your premise is that the
x.5 values are +/- 0.5 in accuracy to start with.
 To demonstrate this take the average of the groups above:
  0.5 + 1.5 + ... 9.5 = 50/10 = 5   (the list of numbers)
  0 + 2 + 2 + ... 10  = 50/10 = 5   (Rounded to Even)
  1 + 2 + 3 + ... 10  = 55/10 = 6   (Rounded Up)

Rounding by adding 0.5 to x.5 results in a number that is different from
the original by the same amount that subtracting 0.5 from x.5 would
yield.

In other words, rounding 0.5 to 0 adds no more imprecision than rounding
to 1.

Having now stated that Round to Even does not increase the imprecision,
I must also state that neither does it does it increase the precision.
What Round to Even accomplishes is most valuable when accumulating a set
of values, since it tends to center the accumulated result in the range
of accuracy, while the Round Up method approaches the upper bound of the
accuracy range, and performing a truncate forces the result to the lower
bound of the accuracy range.

The original question in this thread was (essentially):
 "How do you round a number?"

When I encounter a task that requires rounding, I first consider what
the appropriate method might be and then implement the most reasonable
solution.
 For some jobs, I might just truncate; for others add 0.5 and truncate
(which is Round Up); but, if the rounded values are being accumulated I
(may) use the Round to Even methodology.

But, if you ask me "how do you round a number," my reply is round up if
greater than 0.5, round down if less than 0.5 and if exactly x.5, round
up if previous digit odd, round down if previous digit even.


David W. Gulley
Destiny Designs

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2001\06\02@101114 by michael brown

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> I guess, I'm an exception. I don't personally know any other self taught
> engineers so I can't say how it stacks up but, my gut instinct is that you
> are right Bill. I do know two degreed engineers who don't have a good feel
> for mathematics, both close personal friends, and they both got out of
> design engineering (one does engineering project management and the other
> cranks out asp web code).
>
> Paul
You know me, sort of anyway!  Although, I wouldn't rise to call my self an
"engineer", just a guy that loves to play with electricty, computers and
math.  I like to learn everything the "hard way", hopefully it will stick
better that way.  The guy cranking out the asp code is making some bucks,
isn't he?  I still think you should round at the end and not all along the
way. ;-D

michael

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2001\06\02@121914 by Thomas McGahee

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Sigh.... I did not say .99999 I said .99999 REPEATING.
As in **forever**.

Do not get confused between the VALUE of a number and its
representation. Whether you like it or not, mathematically the mumber
1 exactly equals .9 repeating. This is not a matter of personal
opinion. It is simple mathematical fact.

Fr. Tom McGahee

{Original Message removed}

2001\06\02@145026 by Chris Carr

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> Do not get confused between the VALUE of a number and its
> representation. Whether you like it or not, mathematically the mumber
> 1 exactly equals .9 repeating. This is not a matter of personal
> opinion. It is simple mathematical fact.
>
Now if I remember my maths correctly 0.9 repeating to infinity will
equal 1........but..........you can never reach infinity, you can only
"Approach Infinity".  So whilst 0.9 repeating will get so mind boggling
close to 1
that an amoeba couldn't push his reproductive organ in the gap it will
never actually reach the point where it will equal 1.

Chris Carr

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2001\06\02@152744 by Thomas McGahee

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I really do not want to keep this discussion about .9 repeating
being exactly equal to 1 going and going and going, but as
an educator I really want to make sure that at least some of the
PIC list members "get it".

9/9 is a RATIONAL number. It can be **represented** in decimal
notation in (at least) two ways that LOOK different but have the same
exact VALUE. These are 1.000 (with the zero repeating forever),
and .999 with the 9 repeating forever. The mathematical difference
between the two is .000 with the zero repeating forever.

This concept is difficult for some people to grasp at first,
because .9999 (9 repeating) just LOOKS smaller than 1.0 (0 repeating).

Looks can be VERY deceiving.
777/777 may **look** bigger than .001/.001 to some
people, but believe me the VALUE is the same. 1.

Fr. Tom McGahee

{Original Message removed}

2001\06\02@184812 by Bill Westfield

face picon face
> Now if I remember my maths correctly 0.9 repeating to infinity will equal
> 1........but..........you can never reach infinity, you can only "Approach
> Infinity".  So whilst 0.9 repeating will get so mind boggling close to 1
> that an amoeba couldn't push his reproductive organ in the gap it will
> never actually reach the point where it will equal 1.

You don't have to "reach" infinity.  You SAID that it repeats to infinity,
so it DOES.  It doesn't matter that you can't write it down...

BTW, the "half way" problem is equivilent to 0.1111 repeating in BINARY,
and that's 1.0 too.  The mathematician shouldn't have had a problem.  (The
Philosipher, on the other hand...)

And amoebas don't have reproductive organs...

BillW

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2001\06\02@204500 by michael brown

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---- Original Message -----
From: "Thomas McGahee" <tom_mcgaheeSTOPspamspamSIGMAIS.COM>
To: <PICLISTSTOPspamspamKILLspamMITVMA.MIT.EDU>
Sent: Saturday, June 02, 2001 11:19 AM
Subject: Re: [OT]: Brain Burp Rounding??


> Sigh.... I did not say .99999 I said .99999 REPEATING.
> As in **forever**.
>
> Do not get confused between the VALUE of a number and its
> representation. Whether you like it or not, mathematically the mumber
> 1 exactly equals .9 repeating. This is not a matter of personal
> opinion. It is simple mathematical fact.
>
> Fr. Tom McGahee

Yeah, thats the ticket.......  And infinity < 2*infinity.........


>
> {Original Message removed}

2001\06\02@212246 by michael brown

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----- Original Message -----
From: "Chris Carr" <@spam@nyed.....spamspamBTINTERNET.COM>
To: <spamPICLIST.....spam.....MITVMA.MIT.EDU>
Sent: Saturday, June 02, 2001 1:47 PM
Subject: Re: [OT]: Brain Burp Rounding??


{Quote hidden}

Precisely! The fact that the number is "repeating" implies infinity as a
piece of the formula.

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2001\06\02@212716 by michael brown

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----- Original Message -----
From: "Thomas McGahee" <tom_mcgahee.....spamSIGMAIS.COM>
To: <KILLspamPICLISTspam_OUTspamMITVMA.MIT.EDU>
Sent: Saturday, June 02, 2001 2:30 PM
Subject: Re: [OT]: Brain Burp Rounding??


{Quote hidden}

Don't forget the 1 at position 'infinity + 1'

>
> This concept is difficult for some people to grasp at first,
> because .9999 (9 repeating) just LOOKS smaller than 1.0 (0 repeating).

It is.

>
> Looks can be VERY deceiving.
> 777/777 may **look** bigger than .001/.001 to some
> people, but believe me the VALUE is the same. 1.

In this I have no problem.

{Quote hidden}

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2001\06\02@222346 by David VanHorn

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At 07:39 PM 6/2/01 -0500, michael brown wrote:
>---- Original Message -----
>From: "Thomas McGahee" <spam_OUTtom_mcgaheeTakeThisOuTspamEraseMESIGMAIS.COM>
>To: <EraseMEPICLISTspamBeGonespamKILLspamMITVMA.MIT.EDU>
>Sent: Saturday, June 02, 2001 11:19 AM
>Subject: Re: [OT]: Brain Burp Rounding??
>
>
> > Sigh.... I did not say .99999 I said .99999 REPEATING.
> > As in **forever**.
> >
> > Do not get confused between the VALUE of a number and its
> > representation. Whether you like it or not, mathematically the mumber
> > 1 exactly equals .9 repeating.

hold on jack..

That's as nonsensical as saying that 2=3 for large values of 2.

I have a problem with that.

0.99(followed by any finite or infinite number of nines) is by definition,
not equal to 1.0

The value of 0.99(inf..) is less than 1.0 by an infinitely small (but
non-zero) amount.




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2001\06\02@223902 by Bob Ammerman

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Sorry Dave,

He's right and you are wrong.

The value .9 repeating is the same as the infinite series:

9/10 + 9/100 + 9/1000 + 9/10000 + ...

Which sums to 1.

Remember --- infinite is infinite. If you carry the series out infinitely
there will be _no_ 'residual'.

We have the same thing in binary where

.1 repeating (binary) is the same as the infinite series:

1/2 + 1/4 + 1/8 + 1/16 + ...

Which again, after summing an infinite number of terms, comes to exactly 1.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\06\02@224305 by Jinx

face picon face
> .1 repeating (binary) is the same as the infinite series:
>
> 1/2 + 1/4 + 1/8 + 1/16 + ...
>
> Which again, after summing an infinite number of terms, comes to
> exactly 1.

Wouldn't it come infinitely close to 1 ?

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2001\06\02@225948 by David VanHorn

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At 10:35 PM 6/2/01 -0400, Bob Ammerman wrote:
>Sorry Dave,
>
>He's right and you are wrong.
>
>The value .9 repeating is the same as the infinite series:
>
>9/10 + 9/100 + 9/1000 + 9/10000 + ...
>
>Which sums to 1.

It sums to almost one. The degree of "almost" is a function of your patience.
As you expand the sequence, the difference becomes small, but it is never zero.

You claim 1 = 0.9...
Is it then true that 1(inf) = 0.9...(inf)?

There may be a rule which says so (Which I suspect exists to avoid ugly
problems in calculation), but you're not going to convince me that a number
which is "less than 1 by an infinitely small amount" is equal to 1.


Next, you'll want to sell me 5 pounds of potatoes multiplied by the Sqrt of
-1 :)


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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\02@231056 by Andrew Warren

face
flavicon
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"Thomas McGahee" <RemoveMEtom_mcgaheespamBeGonespamspamSIGMAIS.COM> wrote, over and over and
over:

> Whether you like it or not, mathematically the mumber 1 exactly
> equals .9 repeating.

and David VanHorn <@spam@PICLISTspamspamMITVMA.MIT.EDU> replied:

> That's as nonsensical as saying that 2=3 for large values of 2.
> ....
>
> 0.99(followed by any finite or infinite number of nines) is by
> definition, not equal to 1.0
>
> The value of 0.99(inf..) is less than 1.0 by an infinitely small (but
> non-zero) amount.

   [Sorry to single you out, Dave; this applies not only to you,
   but to everyone else who's posted essentially the same thing.]

It's been a long time since I've written a "God DAMN it, you peopole
are pissing me off" email to the PICLIST, and since James Newton has
imposed a "no profanity" rule, I guess I won't write one now.

Still, though, you people ARE pissing me off.  0.9 repeating IS
exactly equal to 1.  Someone posted a simple algebraic explanation
earlier; was that TOO simple?  Here, for your edification, is a more
complex explanation, courtesy of the sci.math FAQ (where the
"0.999... = 1" question used to be #1 on the list):

11Q:  Why is 0.9999... = 1?

A:  In modern mathematics, the string of symbols "0.9999..." is
   understood to be a shorthand for "the infinite sum  9/10 + 9/100
   + 9/1000 + ...." This in turn is shorthand for "the limit of the
   sequence of real numbers 9/10, 9/10 + 9/100, 9/10 + 9/100 +
   9/1000, ..."  Using the well-known epsilon-delta definition of
   limit, one can easily show that this limit is 1.  The statement
   that 0.9999...  = 1 is simply an abbreviation of this fact.

                   oo              m
                  ---   9         ---   9
       0.999... = >   ---- = lim  >   ----
                  --- 10^n  m->oo --- 10^n
                  n=1             n=1


       Choose epsilon > 0. Suppose delta = 1/-log_10 epsilon, thus
       epsilon = 10^(-1/delta). For every m>1/delta we have that

       |  m           |
       | ---   9      |     1          1
       | >   ---- - 1 | = ---- < ------------ = epsilon
       | --- 10^n     |   10^m   10^(1/delta)
       | n=1          |

       So by the (epsilon-delta) definition of the limit we have

              m
             ---   9
        lim  >   ---- = 1
       m->oo --- 10^n
             n=1

Does that make it clearer?

It's a basic mathematical FACT that 0.9 repeating is equal to 1.  If
you don't "get" this, ask questions.  Say, "Gee, that sure seems
counter-intuitive."  Find your old schoolbooks and see if it's
explained there.  Post a message to the sci.math newsgroup if you
want a thousand people to tell you to read the FAQ... But for God's
sake, if you just can't understand it no matter how hard you try,
don't ARGUE about it; that does nothing but advertise your
unwillingness or inability to learn.

-Andy


=== Andrew Warren - TakeThisOuTfastfwdKILLspamspam@spam@ix.netcom.com
=== Fast Forward Engineering - San Diego, CA
=== http://www.geocities.com/SiliconValley/2499

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2001\06\02@231932 by Alexandre Domingos F. Souza

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>It's been a long time since I've written a "God DAMN it, you peopole
>are pissing me off" email to the PICLIST, and since James Newton has
>imposed a "no profanity" rule, I guess I won't write one now.

       Hmmm...got stressed. It's bad.

>Still, though, you people ARE pissing me off.  0.9 repeating IS
>exactly equal to 1.  Someone posted a simple algebraic explanation
>earlier; was that TOO simple?  Here, for your edification, is a more
>complex explanation, courtesy of the sci.math FAQ (where the
>"0.999... = 1" question used to be #1 on the list):

       So tell me why my teacher doesn't let me go to the next class/year if I mark 4.9 on her exam??? :o)))


---8<---Corte aqui---8<----

Alexandre Souza
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http://planeta.terra.com.br/lazer/pinball/

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2001\06\02@232157 by Jim Paul

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who cares?
-----Original Message-----
From: Andrew Warren <KILLspamfastfwdspamTakeThisOuTIX.NETCOM.COM>
To: TakeThisOuTPICLISTspamspam_OUTMITVMA.MIT.EDU <RemoveMEPICLISTspamspamSTOPspamMITVMA.MIT.EDU>
Date: Saturday, June 02, 2001 10:14 PM
Subject: [OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding??")


"Thomas McGahee" <.....tom_mcgaheeEraseMEspamSIGMAIS.COM> wrote, over and over and
over:

> Whether you like it or not, mathematically the mumber 1 exactly
> equals .9 repeating.

and David VanHorn <spamBeGonePICLISTspamRemoveMEMITVMA.MIT.EDU> replied:

> That's as nonsensical as saying that 2=3 for large values of 2.
> ....
>
> 0.99(followed by any finite or infinite number of nines) is by
> definition, not equal to 1.0
>
> The value of 0.99(inf..) is less than 1.0 by an infinitely small (but
> non-zero) amount.

   [Sorry to single you out, Dave; this applies not only to you,
   but to everyone else who's posted essentially the same thing.]

It's been a long time since I've written a "God DAMN it, you peopole
are pissing me off" email to the PICLIST, and since James Newton has
imposed a "no profanity" rule, I guess I won't write one now.

Still, though, you people ARE pissing me off.  0.9 repeating IS
exactly equal to 1.  Someone posted a simple algebraic explanation
earlier; was that TOO simple?  Here, for your edification, is a more
complex explanation, courtesy of the sci.math FAQ (where the
"0.999... = 1" question used to be #1 on the list):

11Q:  Why is 0.9999... = 1?

A:  In modern mathematics, the string of symbols "0.9999..." is
   understood to be a shorthand for "the infinite sum  9/10 + 9/100
   + 9/1000 + ...." This in turn is shorthand for "the limit of the
   sequence of real numbers 9/10, 9/10 + 9/100, 9/10 + 9/100 +
   9/1000, ..."  Using the well-known epsilon-delta definition of
   limit, one can easily show that this limit is 1.  The statement
   that 0.9999...  = 1 is simply an abbreviation of this fact.

                   oo              m
                  ---   9         ---   9
       0.999... = >   ---- = lim  >   ----
                  --- 10^n  m->oo --- 10^n
                  n=1             n=1


       Choose epsilon > 0. Suppose delta = 1/-log_10 epsilon, thus
       epsilon = 10^(-1/delta). For every m>1/delta we have that

       |  m           |
       | ---   9      |     1          1
       | >   ---- - 1 | = ---- < ------------ = epsilon
       | --- 10^n     |   10^m   10^(1/delta)
       | n=1          |

       So by the (epsilon-delta) definition of the limit we have

              m
             ---   9
        lim  >   ---- = 1
       m->oo --- 10^n
             n=1

Does that make it clearer?

It's a basic mathematical FACT that 0.9 repeating is equal to 1.  If
you don't "get" this, ask questions.  Say, "Gee, that sure seems
counter-intuitive."  Find your old schoolbooks and see if it's
explained there.  Post a message to the sci.math newsgroup if you
want a thousand people to tell you to read the FAQ... But for God's
sake, if you just can't understand it no matter how hard you try,
don't ARGUE about it; that does nothing but advertise your
unwillingness or inability to learn.

-Andy


=== Andrew Warren - .....fastfwdEraseMEspamix.netcom.com
=== Fast Forward Engineering - San Diego, CA
=== http://www.geocities.com/SiliconValley/2499

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2001\06\02@233849 by Jinx

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> 11Q:  Why is 0.9999... = 1?
>
> A:  In modern mathematics,

Modern mathematics. Not old common sense and logic

That's where I make a distinction and where my query about
0.999999r being infinitely close to 1 came from - a logical point
of view, not arguing mathematical proofs. If mathemeticians
in a mathematical world choose to represent 0.99999r as 1 then
I have no problem with that and respect your opinion Andrew

In the physical world "a miss is as good as a mile"

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2001\06\02@233934 by David VanHorn

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>
>It's been a long time since I've written a "God DAMN it, you peopole
>are pissing me off" email to the PICLIST, and since James Newton has
>imposed a "no profanity" rule, I guess I won't write one now.

I'm sorry it's so upsetting to you.

0.9 is different from 1 by a tenth part.
0.99, by a hundredth.
No matter how far you go, the difference is still not zero.
It may become awkward to calculate, but tossing the remainder doesn't seem
fair.

You're telling me that I can take infinity as the number that makes
(1/N)*(1-0.9) = (1/N)*0 true.
It seems that it all hinges on what infinity means, and since people like
Feynman and Hawking are having trouble with calculations where infinity
pops in, I'm not bothered that it causes me trouble.

Still, science is that which, when you stop believing in it, is still works.
Can you show me something by which this is a consequence?
Something physical, that requires this to be true?
Or is this just a peculiarity of the current rule set.

It wasn't that long ago that "zero" didn't exist in mathmatics. I'm sure
the scholars of that day thought their mathematics was quite complete and
correct as well.


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'[OT]: Brain Burp Rounding??'
2001\06\03@003649 by James Newton. Admin 3

face picon face
"...by an infinitely small (but non-zero) amount...."

To paraphrase a popular space opera "Never underestimate the power of the
infinity." Infinity is a mind-numbingly large (or small) thing. A totally
incomprehensible value. Anyone who can actually understand it's magnitude,
would be insane. It is one of the many things in life that one must not try
to completely investigate but rather to, at some point, simply accept.

I always enjoyed a story that a teacher of mine told about a class of
juvenal delinquents that he once enjoyed and tried to inspire. He told them
that they could not walk from one end of a class room to the other. He felt
that in a class of "normal" kids, the students would have sat, smiling,
waiting for the teacher to go on, but in this class one of the kids popped
up, walked to the back wall, then to the front then said "shows what you
know, sucker" and sat down to the applause of his classmates. The teacher
then went on to explain that in order to walk from one end to the other, you
first must walk half way. But then to complete the task, you have to walk
half the remaining distance, and so on (here it comes) * infinitely * so
that you never actually reach the other end, because you always have half
way left to go. The kids thought about it and then one said, "that's bull
shit teach, I know can still walk all the way" and  another said "no man,
he's right, you can get that close, but you actually never get there!" And
before the shanks came out, the teacher said "Does it really make a
difference? Can you get close enough that it doesn't matter? If you just
keep walking WILL YOU STILL BREAK YOUR NOSE!!!???" and the kids were willing
to accept that it probably isn't a good thing to understand that you can't
actually get from one wall to another.

Anyway, the point is, if you can believe that you can walk from one end of a
room to the other, then you can believe that infinitely small IS zero and
that 4.999 repeating is 5 and that you need to round even to avoid bias.

In fact, this is the main difference between engineers and technicians. The
difference between things making sense and things working.

James Newton, PICList Admin #3
spamjamesnewtonspam_OUTspam@spam@piclist.com
1-619-652-0593 phone
http://www.piclist.com


{Original Message removed}

2001\06\03@003717 by Bob Ammerman

picon face
----- Original Message -----
From: "Jinx" <spamjoecolquitt@spam@spamSTOPspamCLEAR.NET.NZ>
To: <spamBeGonePICLISTspamBeGonespam@spam@MITVMA.MIT.EDU>
Sent: Saturday, June 02, 2001 10:42 PM
Subject: Re: [OT]: Brain Burp Rounding??


> > .1 repeating (binary) is the same as the infinite series:
> >
> > 1/2 + 1/4 + 1/8 + 1/16 + ...
> >
> > Which again, after summing an infinite number of terms, comes to
> > exactly 1.
>
> Wouldn't it come infinitely close to 1 ?

Not after an _infinite_ number of terms.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\06\03@003725 by Bob Ammerman

picon face
Dave,

The point is that it does _not_ take patience.

.9 repeating is already an _infinite_ series. Not just a "sorta infinite as
long as you want to go on" series.

Its value is exactly 1.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\06\03@005515 by David VanHorn

flavicon
face
>
>Anyway, the point is, if you can believe that you can walk from one end of a
>room to the other, then you can believe that infinitely small IS zero and
>that 4.999 repeating is 5 and that you need to round even to avoid bias.

That's Zeno's Paradox, and the problem is that they kept decreasing the
time intervals over which the motion was made. (Half the distance, in half
the time) The paradox points out only that you can't really make those
measurements, not that you can't get there.
Indeed, you'll MUCH sooner cross the quantum uncertanity limit, where you
can't say where you are, and how fast you're moving.
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2001\06\03@010945 by David VanHorn

flavicon
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At 12:18 AM 6/3/01 -0400, Bob Ammerman wrote:
>Dave,
>
>The point is that it does _not_ take patience.
>
>.9 repeating is already an _infinite_ series. Not just a "sorta infinite as
>long as you want to go on" series.

At each point, it evaluates to <1. Repeating it in smaller steps forever
doesn't change that.
Show me the point at which it changes, and evaluates to 1.
I know, it's infinitely far away, and it can never be reached, but if you
wish real hard...

>Its value is exactly 1.

Can you show any physical thing that requires this to be true?


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2001\06\03@015012 by David VanHorn

flavicon
face
>
>Its value is exactly 1.

So I did a little digging, and found this link.
http://www.maths.abdn.ac.uk/~igc/tch/ma1002/appl/node57.html

However, all that is said about a converging series is that you can
determine a value that it approaches.  I see no requirement or statement
that it REACHES that value.

Here also,
http://forum.swarthmore.edu/dr.math/problems/may7.8.98.html

S = 1/2 + 1/4 + 1/8 + 1/16 + ... + 1/2^n + ...

This series is described as convergent (obvious) and approaching 1, but not
described as being  equal to 1

Here:
http://www.misd.wednet.edu/~kim_schjelderup/Integrated%203/Pages/Seq&Series/4.7l%20Inifinite%20Series%20(WP).pdf

Finally the statement:
If the sequence of partial sums of an infinite series has a limit, then
that limit is the sum of the series.

Looks to me like we are defining "sum of the series" as something special,
and we are not saying that the series is equal to the limit, in a manner
similar to the way that "spin" is used in quantum mechanics.

It's certainly useful in calculation, because it causes those awkward
infinities to dissapear, by ignoring the infinitely tiny difference between
the actual result, and the defined result.

Inverting Zeno's paradox, the fallacy is that a finite distance (or number)
does not become infinite, simply because it can be divided into an infinte
number of smaller distances (or numbers)




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2001\06\03@024811 by michael brown

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----- Original Message -----
From: "David VanHorn" <RemoveMEdvanhornRemoveMEspamRemoveMECEDAR.NET>
To: <PICLISTKILLspamspamspamMITVMA.MIT.EDU>
Sent: Saturday, June 02, 2001 9:57 PM
Subject: Re: [OT]: Brain Burp Rounding??


{Quote hidden}

patience.
> As you expand the sequence, the difference becomes small, but it is never
zero.
>
> You claim 1 = 0.9...
> Is it then true that 1(inf) = 0.9...(inf)?
>
> There may be a rule which says so (Which I suspect exists to avoid ugly
> problems in calculation), but you're not going to convince me that a
number
> which is "less than 1 by an infinitely small amount" is equal to 1.
>
>
> Next, you'll want to sell me 5 pounds of potatoes multiplied by the Sqrt
of
> -1 :)
I'm with Dave on this one.  Sqrt of -1 = i    "i" - that amazingly
ridiculous, non-existant value that allows mathematicians to continue on
creating even more ridiculous mathematics coming up with answers that don't
(can't) exist.  Sort of like "e" the fascinating irational number that
somehow ocupies an exact position on a number line.  Where as pi is a
supposedly "irrational" number easily represented as a fraction (which by
definition makes it rational) as in pi = C/D  where C is some number
representing circumfrence and D representing diameter of a circle.  You
cannot use infinity in an equation and expect any sanity in the result.
However, we are supposed to accept these things and then also believe that
you cannot divide by 0 (answer is undefined even though the real answer
should be infinity).  Since division is nothing but repetive subtraction,
you can easily prove (using a pic ;-D ) that dividing by 0 is infinite and
not "undefined".  Look Dave its true 1=2 ;-)

    a = x            [true for some a's and x's]
  a+a = a+x          [add a to both sides]
   2a = a+x          [a+a = 2a]
2a-2x = a+x-2x       [subtract 2x from both sides]
2(a-x) = a+x-2x       [Factor left side]
2(a-x) = a-x          [Simplify right side]
    2 = 1            [divide both sides by a-x]

Of course we can't divide by zero, which is precisely what happens in the
last step.  Back to the .999 rpt.=1 arithmetic with infinity is NOT allowed,
because infinity is not a number. And, just like our little puzzle, we get
answers that make no sense.

>

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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@025229 by michael brown

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----- Original Message -----
From: "Andrew Warren" <spam_OUTfastfwd@spam@spamIX.NETCOM.COM>
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Sent: Saturday, June 02, 2001 10:10 PM
Subject: [OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding??")


{Quote hidden}

Now, without trying to upset anyone, I find it hard to believe that an FAQ
is the end all answer to this.

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2001\06\03@025845 by Bill Westfield

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>> In the physical world "a miss is as good as a mile"

In the physical world, you don't need to get anywhere NEAR an infinite
number of 9s after your decimal point for .999... to be "equal to" 1.0
Say you're talking meters - at about 10 9s ("0.9999999999 m") you're about
one atomic diameter from 1.0

BillW

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2001\06\03@030711 by Bill Westfield

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   It seems that it all hinges on what infinity means, and since people like
   Feynman and Hawking are having trouble with calculations where infinity
   pops in, I'm not bothered that it causes me trouble.

Infinity is fun.  Not very intuitive, but fun.  The sort of infinity we're
talking about here is pretty well understood, mathematically.  Someone said
recently here that "infinity < (2 * infinity)"  Sorry, that's wrong.
       infinity = 2*infinity
Furthermore, you have bits like the number of integers is the same as the
number of real numbers (infinity, aleph-null (?), "countably infinite"), but
the number of irrational numbers is larger ("uncoutably infinite")

   Can you show me something by which this is a consequence?
   Something physical, that requires this to be true?

Physical things don't require infinity to work...  See previous message
about atomic diameters...

   Or is this just a peculiarity of the current rule set.
Sure.  That's "all."

BillW

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'[OT]: Brain Burp Rounding??'
2001\06\03@035319 by Chris Carr

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>
> And amoebas don't have reproductive organs...
>
Are you sure ?

According to the arguments going on here they must have.
Because nothing is the same as infinitely small so....
if they have no reproductive organ they must have
a reproductive organ that is infinitely small.

All this was explained in the service manual for Starship Titanic's
Infinite Improbability Drive. Unfortunately no longer available since
the Starship suffered a Spontaneous Massive Existence Failure.

8-)

Chris Carr

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2001\06\03@043345 by Roman Black

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David VanHorn wrote:

> > > Sigh.... I did not say .99999 I said .99999 REPEATING.
> > > As in **forever**.
> > >
> > > Do not get confused between the VALUE of a number and its
> > > representation. Whether you like it or not, mathematically the mumber
> > > 1 exactly equals .9 repeating.
>

> hold on jack..
> The value of 0.99(inf..) is less than 1.0 by an infinitely small (but
> non-zero) amount.


I'm with you David, if you are going to believe in
the mystical concept of infinity then it has to be
credited both ways. 0.99 (inf) is different to 1.0
by an infinitely small difference. If it was equal
to 1.0 then it would be written as such...

Seems the argument is "does an infinitely small
thing exist?" and I think by the very concept of
infinity the answer has to be yes.
-Roman

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2001\06\03@052228 by Roman Black

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michael brown wrote:

>      a = x            [true for some a's and x's]
>    a+a = a+x          [add a to both sides]
>     2a = a+x          [a+a = 2a]
>  2a-2x = a+x-2x       [subtract 2x from both sides]
> 2(a-x) = a+x-2x       [Factor left side]
> 2(a-x) = a-x          [Simplify right side]
>      2 = 1            [divide both sides by a-x]
>
> Of course we can't divide by zero, which is precisely what happens in the
> last step.


Actually I think I proved this with one of
my early PC programming experiments. I programmed
it to "divide N by zero", and yes, the PC sat there
for an *infinitely* long time.... I think other PC
programmers may have duplicated my test results,
Microsoft have done some astounding research in
this field... ;o)
-Roman

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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@053058 by Roman Black

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Andrew Warren wrote:

{Quote hidden}

Hmmm. I feel like the child in the "emperors new
clothes". These experts all backing each other up re
what they agree is "right". Sort of like politicians
but with better formulas. ;o)

Surely any child could point out that with the
0.9999 issue that ANY POSSIBLE STEP can only reduce
the error to a smaller amount. The *number* of steps
is completely confusing and superfluous, the error
must always exist as there is NO POSSIBLE STEP
that can eliminate the error, only reduce it a bit
more. And you really don't need impressive formulas
to understand that reality? :o)
-Roman

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'[OT]: Brain Burp Rounding??'
2001\06\03@090310 by Bob Ammerman

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----- Original Message -----
From: "David VanHorn" <spamdvanhornKILLspamspamKILLspamCEDAR.NET>
To: <spamPICLISTspam_OUTspamMITVMA.MIT.EDU>
Sent: Sunday, June 03, 2001 12:58 AM
Subject: Re: [OT]: Brain Burp Rounding??


> At 12:18 AM 6/3/01 -0400, Bob Ammerman wrote:
> >Dave,
> >
> >The point is that it does _not_ take patience.
> >
> >.9 repeating is already an _infinite_ series. Not just a "sorta infinite
as
> >long as you want to go on" series.
>
> At each point, it evaluates to <1. Repeating it in smaller steps forever
> doesn't change that.

> Show me the point at which it changes, and evaluates to 1.

It doesn't change at any given step, yet, _after_ infinite steps (if one can
comprehend that), in the _limit_ that is its value.

> I know, it's infinitely far away, and it can never be reached, but if you
> wish real hard...
> >Its value is exactly 1.

Show me where infinity is and I'll show you the 'point' you are looking for.

>
> Can you show any physical thing that requires this to be true?
>

Obviously not, physical reality is limited by Heisenburg, quantum effects,
etc.

>
> --
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Bob Ammerman
RAm Systems
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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@092443 by Bob Ammerman

picon face
>
> Surely any child could point out that with the
> 0.9999 issue that ANY POSSIBLE STEP can only reduce
> the error to a smaller amount. The *number* of steps
> is completely confusing and superfluous, the error
> must always exist as there is NO POSSIBLE STEP
> that can eliminate the error, only reduce it a bit
> more. And you really don't need impressive formulas
> to understand that reality? :o)
> -Roman


Roman, thank you. You gave me the words to deal with this.
Above, you said:

"The *number* of steps is completely confusing and superfluous"

However, 'infinitely many steps' is _not_ a number of steps. Rather it is
the process carried out for (if I may) an _infinite_ number of steps.

Remember: 'infinity' is not a number, its a concept.

That is the difference.

Bob Ammerman
RAm Systems
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'[OT]: Brain Burp Rounding??'
2001\06\03@095955 by Alexandre Domingos F. Souza

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>In fact, this is the main difference between engineers and technicians. The
>difference between things making sense and things working.

       HUAHUHAUHAUHAUHUAHUHAUHA, I think this one brings an end to this thread :oD Congratulations James!


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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@110451 by David W. Gulley

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Earlier in this thread, the most simple (IMO)) proof that
0.999(Repeating) = 1 was shown using no magic, mirrors or divides by 0.

There are 3 thirds in a whole (ie 3*(1/3) = 1)
 and, 1/3 = 0.33333333(repeating forever) (divide it out and see!)
   Multiply that by 3 and get 0.99999999(repeating forever) (try it!)

   Therefore 1 = 0.99999999(repeating forever)

It may be uncomfortable, but it is true!

Show me any flaw, trick, or error in this example.

David W. Gulley
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2001\06\03@112351 by Alexandre Domingos F. Souza

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>Earlier in this thread, the most simple (IMO)) proof that
>0.999(Repeating) = 1 was shown using no magic, mirrors or divides by 0.
> There are 3 thirds in a whole (ie 3*(1/3) = 1)
>  and, 1/3 = 0.33333333(repeating forever) (divide it out and see!)
>    Multiply that by 3 and get 0.99999999(repeating forever) (try it!)
>    Therefore 1 = 0.99999999(repeating forever)
>It may be uncomfortable, but it is true!
>Show me any flaw, trick, or error in this example.

       It seems to be something like "angel's gender" but let's revise it.

       When you part one something MATERIAL (numbers aren't material, they just TRY to represent it), you get three thirds. One equals another. That's ok.

       When you divide the number one, by three, you get ALMOST three equal parts. ALMOST because a calculator cannot represent the part who tend to infinity. If you divide something physical, you can get all three parts with the same volume or weight. But a calculator cannot represent this.

       When you bring these three parts togheter (ops, where is my english lexican?) it becomes 1 again. But in a calculator, that ROUND NUMBERS PER SE, it will not bring you the same result. It's valid for any calcule that brings the "dizima periodica" (anyone who speaks portuguese, can tell me how we say this expression in english? It means the infinite .33333333 of the 1/3), because a calculator has a limit of HOW FAR can it store numbers.

       So, I think it's nice to speak that 0.9999999999999 TENDS to 1. But it can never be 1.

       And of course, In my HP48 I trust :o) And it gives me 0.99999999999999 when I multiply 0.33333333333 x 3 :o)


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2001\06\03@112409 by David Covick

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You trust your calculator? :)

----- Original Message -----
From: "David W. Gulley" <EraseMEdgulleyspamKILLspamDESTINYDESIGNS.COM>
To: <EraseMEPICLISTRemoveMEspamMITVMA.MIT.EDU>
Sent: Sunday, June 03, 2001 7:57 AM
Subject: Re: [OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding??")


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2001\06\03@113013 by Alexandre Domingos F. Souza

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>You trust your calculator? :)

       In HP I trust :o)

       It remembers me an old phrase...

       "In God we trust. All others pay cash"


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2001\06\03@121951 by michael brown

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----- Original Message -----
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Sent: Sunday, June 03, 2001 9:57 AM
Subject: Re: [OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding??")


{Quote hidden}

IMnotsoHO the only flaw here is that many simple ratios cannot be precisely
represented by decimal notation.  But (being ignorant and hard headed) I
still fail to see how this proves anything except that decimal notation is
sometimes imprecise.  I guess it only serves to show that mathematics (much
like statistics) can be used (and abused) to show that anything is true.
Sort of like geometry, being based on axioms and postulates, where we
"assume" that certain basics are true.  Then we take these things and
extrapolate further information using "proofs".  How can we really say that
these "proofs" prove anything, when they are entirely based upon assumptions
(granted that these assumptions have never been shown to be false, yet).  I
realize that this is more philosophy than math but I cannot resist. ;-D
When taken to an extreme simple logic, reasoning and mathematics can be
shown to fall apart.  Mathematical infinity is such an extreme.  Taking
Kepler's laws of motion as an example, they worked fine most of the time
(until simple observation of Mercury indicated that something was critically
wrong).  Enter Albert Einstein who showed us why they didn't always work,
while introducing a new world of paradox's and problems such as parallel
lines that eventually meet.  Even the so-called "Big Bang Theory" relies on
an "assumption" that during the first miniscule amount of time after the
bang that all of the apparant "laws" of physics and quantum mechanics were
somehow not in effect.  Mathematics is flawed, plain and simple.
Demonstrating these flaws and then arguing about them probably serves no
practical purpose.  However without debate and questioning advancement will
not occur.  Standing up and shouting that something is true because an FAQ
says so is not proof, neither is a mathematical proof necessarily equal to
absolute truth.  Nothing has ever really been proved, only temporarily shown
to be apparantly true.  As time rolls on we find that their seems to always
be an exception to the rule.  Reality is not (and never has been) what
mathematics tells us that it is.  Mathematics (like a yard stick) is a
wonderful tool, but it does not dictate absolute truth.  It seems that the
only thing that is sure is that we can never be absolutely sure (only sure
until someone "proves" that we are not).  At any given time througout
history, there exists at least one known mathematical paradox.  This seems
to serve the purpose of contiunally reminding us that something is
fundamentaly wrong with our reasoning.  If people didn't question apparant
truth we would all still be living on a flat earth in a geocentric universe.

michael the fool
(not trying to upset anyone, just trying to stimulate some neurons and
healthy debate)

>
> David W. Gulley
> Destiny Designs

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'[OT]: Brain Burp Rounding??'
2001\06\03@130049 by David VanHorn

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>
>I'm with Dave on this one.  Sqrt of -1 = i    "i" - that amazingly
>ridiculous, non-existant value that allows mathematicians to continue on
>creating even more ridiculous mathematics coming up with answers that don't
>(can't) exist.

Hold on there. Sqrt -1 is a valuable tool, but it is an imaginary number.


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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@131810 by Byron A Jeff

face picon face
On Sun, Jun 03, 2001 at 12:22:50PM -0300, Alexandre Domingos F. Souza wrote:
> >Earlier in this thread, the most simple (IMO)) proof that
> >0.999(Repeating) = 1 was shown using no magic, mirrors or divides by 0.
> > There are 3 thirds in a whole (ie 3*(1/3) = 1)
> >  and, 1/3 = 0.33333333(repeating forever) (divide it out and see!)
> >    Multiply that by 3 and get 0.99999999(repeating forever) (try it!)
> >    Therefore 1 = 0.99999999(repeating forever)
> >It may be uncomfortable, but it is true!
> >Show me any flaw, trick, or error in this example.
>
>         It seems to be something like "angel's gender" but let's revise it.
>
>         When you part one something MATERIAL (numbers aren't material, they just TRY to represent it), you get three thirds. One equals another. That's ok.
>
>         When you divide the number one, by three, you get ALMOST three equal parts. ALMOST because a calculator cannot represent the part who tend to infinity. If you divide something physical, you can get all three parts with the same volume or weight. But a calculator cannot represent this.
>

But this is exactly the point. When you divide the number 1 by 3 you get
exactly (note EXACTLY!!!!) 3 equal parts. However the representation of that
exactly is .3 (repeating).

Everyone is getting confused by the repeating. "There is a difference at
every step therefore there must be a difference at the 'infinite' step." is
close to the quote I've read in this thread.

There is no infinite step. The threes stop ending at the same place that
you find the biggest integer! Now would anyone care to discuss what the
biggest integer is?

The repeating series is the only way to represent the value exactly. Any
attempt to cut off the repeating and it's no longer an exact representation.
You have to take the baby with the bathwater. 1/3 is exactly .3 (repeating) and
three times each value is 1 and .9 (repeating) which are exactly (note
EXACTLY!!!) the same.

And no finite string of 3's or 9's, no matter how long the string is is
exactly equal to the infinitely repeating string. And that's why this works.
Any attempt to make the string finite gives a value less than the exact value.
However the infinite string is the exact value.

Let's consider a couple of cases. Consider two numbers x1 and x2. x1 is
exactly equal to 9 (repeating). x2 is equal to 2^1024 9's after the decimal
point (a lot of 9's to be sure). Now we should be able to agree on a couple
of things.

1) That x1 > x2. x1 has more 9's than x2, so it's bigger.
2) That 10*x2 - x2 is less than 9. Consider:

10 * 0.9999 (2^1024 of them) = 9.99999 (2^1024 - 1 9's after decimal point)
                 (-x2)       -0.99999 (2^1024 9's after decimal point)
                ---------------------
                              8.99999 (2^1024 -1  9's and a 1 on the end)

No problem right? Now do the same with x1 and you see the difference.

10 * .9 (repeating) = 9.9 (repeating)
                    -0.9 (repeating)
                   -----------------
                     9.0 (repeating)

Now the difference is that since in both cases the .9 (repeating) are exactly
the same. That's the difference with infinity. Arithmetic operations on
infinity result with exactly equal infinite values. That's the catch. With
any finite string, multiplying by 10 and subtracting has a difference however
small. But the same operation on a infinite string gives no, zero, 0 , nada
difference. Not an infintessimally small difference. NO DIFFERENCE!!! It's
like trying to define the smallest real number larger than 0. That number is
0. Sounds strange, but it's true because the limit of an infinite series
approching 0 is 0.

Everyone who's arguing the difference between the sum of an infinite series
and the limit of the series isn't getting that when you deal with infinity
there is no end, therefore there is no difference.

Just remember that to justify your argument you must, absolutely must, be
able to define the largest integer. Once you can do that, then everything
else falls into place.

Good luck. ;-)



>         When you bring these three parts togheter (ops, where is my english lexican?) it becomes 1 again. But in a calculator, that ROUND NUMBERS PER SE, it will not bring you the same result. It's valid for any calcule that brings the "dizima periodica" (anyone who speaks portuguese, can tell me how we say this expression in english? It means the infinite .33333333 of the 1/3), because a calculator has a limit of HOW FAR can it store numbers.
>
>         So, I think it's nice to speak that 0.9999999999999 TENDS to 1. But it can never be 1.
>
>         And of course, In my HP48 I trust :o) And it gives me 0.99999999999999 when I multiply 0.33333333333 x 3 :o)
>

Calculators don't help. They're finite. Infinity has different rules than
finite. I'm sure your calculator also has a largest integer or real that it
can store. So does that mean that the next larger integer or real (which
clearly does exist) does not actually exist because your calculator says so.

So to summarize. 1/3 = .3 (repeating). 3*(1/3) = 3 * .3 (repeating). Therefore
1 = .9 (repeating). End of story.

And by the way if you fell compelled to refute this argument, please bring
along the largest possible integer with you. You'll need it.

BAJ

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2001\06\03@132214 by Alexandre Domingos F. Souza

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       Ok, too crazy to me. Back to binaries :o)


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2001\06\03@134459 by Sebastian Garcia

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| Earlier in this thread, the most simple (IMO)) proof that
| 0.999(Repeating) = 1 was shown using no magic, mirrors or divides by 0.
|  There are 3 thirds in a whole (ie 3*(1/3) = 1)
|   and, 1/3 = 0.33333333(repeating forever) (divide it out and see!)
|     Multiply that by 3 and get 0.99999999(repeating forever) (try it!)
|     Therefore 1 = 0.99999999(repeating forever)
| It may be uncomfortable, but it is true!


Hi,

Leaving behind calculators and computers, mathematically "it can be proof"
(i'm not doing that in this post)that the following are two different
decimal series development for the same number:

1)    1

2)    0.99999999...  (infinite periodic digits)


A quick view: Starting with, for example, the number: 0.999 and "appending"
by steps a 9 to the rightmost digit, the number obtained step by step is
greater. You can find in every step infinite real numbers between  the
number obtained and 1. Remember that in the real set of numbers, there's
always an infinite quantity of numbers between two different numbers. This
is not what it happens in the limit, You can't find infinite (in fact, You
can't find *any* number...) real numbers between  0.999...  and 1.

So the mathematical proof of the equality is based on showing that between
0.9999... and 1 there's not an infinite quantity of real numbers.


Best regards,

S.-

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'[OT]: Brain Burp Rounding??'
2001\06\03@135116 by Byron A Jeff

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On Sat, Jun 02, 2001 at 08:03:04PM -0500, David VanHorn wrote:
{Quote hidden}

Dave,

You need some infinity training. Let's try a few examples:

1) What's the largest integer?
2) What's the value of 1/0?
2A) What's the value of 1/infinity?
3) What's the smallest real number larger than 0? (BTW that's the answer to
your question above)
4) Pick any two real numbers. How many real numbers are between the two?
5) What's the last digit of PI?

It's a simple mathematical fact that once you start dealing with infinity
the rules change. You find your difference above in the same place as the
largest integer and the smallest number bigger than 0. The answer is
infinity and 0. The last one sounds incongruous, but true. That's the nature
of infinity. 1/infinity doesn't approch zero. It doesn't approximate zero. It
isn't infinitely close to zero. IT IS ZERO! EXACTLY ZERO!

There is no difference between 1 and .9 (repeating). Not in infantisimal
difference. No difference. They are the same number. Of course any attempt
to make an infinite value finite make it lose it's infiniteness.

All of this fuss is over trying to attribute infinity to an approximation.
We use approximations to gain understanding in our little finite minds!
But you have to cross over and realize that once something is defined as
infinite, it is no longer an approximation of anything. It's exact.
And the math that works on infinity fails once you express finiteness on it.

The best treatment on the subject I ever read was Issac Asimov's "Asimov on
Numbers". He has several essay's on the nature of infinity.

Just remember that whenever you're having an infinity discussion, that you must
bring the largest integer to the table. Once you know that integer, the rest
is easy.

BAJ

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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\03@165134 by Bill Westfield

face picon face
What about the math proof someone posted a while ago...

x = .999...
10*x = 9.999...
9*x = 10*x - x   (the infinite .9999 cleanly subtract from one another -->)
9*x = 9.999... - .999... = 9.0
x = 1

No divisions by zero or other math-destroying magic required...

BillW

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2001\06\03@173818 by Jinx

face picon face
> What about the math proof someone posted a while ago...
>
> x = .999...
>10*x = 9.999...
> 9*x = 10*x - x   (the infinite .9999 cleanly subtract from one
> another -->)
> 9*x = 9.999... - .999... = 9.0
> x = 1
>
> No divisions by zero or other math-destroying magic required...
>
> BillW

Making something look like something else isn't how "I" define
proof. I'll be blunt and say that type of mathematical manipulation
is just card tricks. And as for "a miss is as good as a mile", look
at the number of particle smashes needed to detect neutrinos or
other sub-atomic bits, which are far far smaller than atoms. How
many head-on collisions were an infinitely small "that much" off ?
But understand that I'm quite comfortable with the fact that there
is a mathematical world and a physical world

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2001\06\03@181128 by Mg

flavicon
face
----- Original Message -----
From: "Jinx"

> But understand that I'm quite comfortable with the fact that there
> is a mathematical world and a physical world

This concept can be seen in 'Donald Duck in Mathematical World'! :)

-Mg

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2001\06\03@232440 by M. Adam Davis

flavicon
face
Reminds me of a mathematician and an engineer in the same class, where
the teacher presents the problem:

Suppose  a beautiful woman (or man, take your pick ;-) is opposite a
room from you, and you can approach her/him with the restriction that
each movement can only halve the distance between you and her/him.  Will
you ever reach her/him?

The mathematician responds:
No.  You may get infinetely close, but you will never reach her/him.

The engineer responds:
You will get close enough for most intents or purposes...


Of course, conceptually, 0.999... does not equal one.  It equals
0.999....  But using calculus and other methods you see that 0.999...
approaches 1, and, for all intents and purposes, is equal to 1.  It
really depends on what level of precision one is asking for.  If one
want infinite precision then one cannot say that 0.999... = 1 unless one
can prove that 0.999... approaches one faster than the needed precision
approaches infinity.

But this is all academic, and is akin to proving that the chicken came
before the eggroll.  If anyone wants to prove me wrong, then sit down
and write a 0, a decimal point, an infinite series of nines, and equal
sign, and a one (no shorthand, please!) before hitting reply.

-Adam

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'[OT]: Brain Burp Rounding??'
2001\06\04@022854 by Russell McMahon

picon face
> 5) What's the last digit of PI?


The last digit of Pi is 4.5, on average


           RM :-)

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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\04@042543 by Andrew Warren

face
flavicon
face
David VanHorn <PICLIST.....spam@spam@MITVMA.MIT.EDU> wrote:

> I'm sorry it's so upsetting to you.

   Thanks, Dave.  I don't know WHY this thread makes me so crazy --
   it really shouldn't -- but I just can't help it.  I know you're
   not deliberately trolling for an argument.

> 0.9 is different from 1 by a tenth part.
> 0.99, by a hundredth.

   Ok, maybe it's easier if we turn the original assertion around:

   What if I said that the DEFINITION of "infinite" is "the number
   of 9s you'd have to append to 0.9 in order to make that number
   equal to 1"?  Would that make sense?

   Perhaps you could look at it in this casual, common-sense way:

   If 0.999... APPROACHES 1 as the number of 9s APPROACHES infinity,
   then 0.999... EQUALS 1 when the number of 9s EQUALS infinity.

   Do either of those approaches help?

> It seems that it all hinges on what infinity means

   Well, yeah.

> people like Feynman and Hawking are having trouble with
> calculations where infinity pops in

   Feynman hasn't been having trouble with ANY calculations since
   he died, and if Hawking could speak, I'm pretty sure he'd tell
   you that 0.999... is equal to 1.

> I'm not bothered that it causes me trouble.

   That's fine... But the fact that you have difficulty with the
   concept isn't a good reason to assert that mathematics is wrong.

> It wasn't that long ago that "zero" didn't exist in mathmatics.

   "Zero" has ALWAYS existed in mathematics: "If Julius has X
   apples, and he gives III to Brutus and VII to Biggus Dickus, how
   many apples remain?"

   It's just the "0" SYMBOL which hasn't always existed.

> I'm sure the scholars of that day thought their mathematics was
> quite complete and correct as well.

   That's an argument AGAINST your point of view, not for it.

   -Andy


=== Andrew Warren - spamBeGonefastfwdspamspam_OUTix.netcom.com
=== Fast Forward Engineering - San Diego, CA
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'[OT]: Brain Burp Rounding??'
2001\06\04@044703 by uter van ooijen & floortje hanneman

picon face
> Next, you'll want to sell me 5 pounds of potatoes multiplied by the Sqrt
of
> -1 :)

Why not, if he pays you with imaginary money?

Wouter

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'[OT]: ENOUGH! (was: "Re: [OT]: Brain Burp Rounding'
2001\06\04@044706 by uter van ooijen & floortje hanneman

picon face
>         So tell me why my teacher doesn't let me go to the next class/year
if I mark 4.9 on her exam??? :o)))

Because you did not score the repeating 9's after the 4.9?

Wouter

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2001\06\04@044709 by uter van ooijen & floortje hanneman

picon face
> > The value of 0.99(inf..) is less than 1.0 y an infinitely small (but
> > non-zero) amount.

> 11Q:  Why is 0.9999... = 1?

Mathematically speaking the propositions "The value of 0.99... is less than
1.0 by an infinitely small amount" and "0.99... = 1" are the same! Maybe
that helps to understand a counter-intuitive fact... Infinitely small must
be interstand as "when I name an amount, *any amount at all*, the infinitely
small number is still smaller". Think of infinitely small as a very verbose
(but very usefull) way of specifying zero. In fact it is this way of
thinking about zero (or equality) that makes calculus possible.

Wouter

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2001\06\04@123552 by David VanHorn

flavicon
face
>
>     What if I said that the DEFINITION of "infinite" is "the number
>     of 9s you'd have to append to 0.9 in order to make that number
>     equal to 1"?  Would that make sense?

No.
If, at any point we can just say "aw to hell with it, it's almost 1, so
it's 1", I have a problem with that.

However, as a tool in calculus, to allow calculations that wouldn't
otherwise be possible, and with the proviso that we are approximating, and
not exactly calculating an answer, I have no problem with it.

The root problem here appears to be that there some numbers which the
decimal system is ill equipped to represent, in a manner similar to roman
numerals having problems with large numbers, only in a deeper manner.

1/3 is easy to deal with, but can't be represented with complete accuracy
in decimal form.


>     Perhaps you could look at it in this casual, common-sense way:
>
>     If 0.999... APPROACHES 1 as the number of 9s APPROACHES infinity,

Ok

>     then 0.999... EQUALS 1 when the number of 9s EQUALS infinity.

No.
I see no requirement that it do so.



>     Feynman hasn't been having trouble with ANY calculations since
>     he died, and if Hawking could speak, I'm pretty sure he'd tell
>     you that 0.999... is equal to 1.

For any practical matter, yes.
However, in an absolute sense, this is just sweeping some ugliness under
the carpet.

> > It wasn't that long ago that "zero" didn't exist in mathmatics.
>
>     "Zero" has ALWAYS existed in mathematics: "If Julius has X
>     apples, and he gives III to Brutus and VII to Biggus Dickus, how
>     many apples remain?"

If you can't represent it, then you can't do calculations with it.


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2001\06\04@131343 by Jeff DeMaagd

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----- Original Message -----
From: David VanHorn <TakeThisOuTdvanhornspamspamCEDAR.NET>

> >     Perhaps you could look at it in this casual, common-sense way:
> >
> >     If 0.999... APPROACHES 1 as the number of 9s APPROACHES infinity,
>
> Ok
>
> >     then 0.999... EQUALS 1 when the number of 9s EQUALS infinity.
>
> No.
> I see no requirement that it do so.
>
> >     Feynman hasn't been having trouble with ANY calculations since
> >     he died, and if Hawking could speak, I'm pretty sure he'd tell
> >     you that 0.999... is equal to 1.
>
> For any practical matter, yes.
> However, in an absolute sense, this is just sweeping some ugliness under
> the carpet.

I haven't seen this used in this thread, so I'll describe it this way, as my
old college calc prof used this as his example, try this:

Using decimal representations:
1/3 = .33333333333 (to infinity)

1/3 * 3 = .3333333333 * 3 = .99999999999 (to infinity)

However, using fracional simplification:
1/3 * 3 = 3/3 = 1/1 = 1

Therefore 1 = .9999999999 (to infinity)

Is that good enough for you?

> If you can't represent it, then you can't do calculations with it.

What is wrong with the overbar? Are you requiring all numeric
representations be in decimal?  So I can't use Pi in any of my calculations?
e?  i?

Jeff

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2001\06\04@132226 by David VanHorn

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face
>
>1/3 * 3 = .3333333333 * 3 = .99999999999 (to infinity)
>
>However, using fracional simplification:
>1/3 * 3 = 3/3 = 1/1 = 1
>
>Therefore 1 = .9999999999 (to infinity)
>
>Is that good enough for you?

Works for me.
It's just awkward to represent in decimal
The fractions don't "simplify" it, they are a better representation.
Simplification implying discarding accuracy to achieve an end.
I'll agree with 1 = the sum of the infinite series 0.999.. strictly as a
simplification, because the result isn't likely to be significantly different.
But I don't agree that 1 = 0.999...
The key point is that by making the first statement, you are defining what
"sum of the infinite series" means, not stating the equality 1 = 0.999...


> > If you can't represent it, then you can't do calculations with it.
>
>What is wrong with the overbar? Are you requiring all numeric
>representations be in decimal?  So I can't use Pi in any of my calculations?
>e?  i?

'Snot what I said.
1/3 is a precise representation, 0.3333 isn't
PI works, 3.141... isn't precise.
When you force any of these trancendentals into decimal form, you can't
represent them accurately. It's a fundamental limitation of the decimal form.


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2001\06\04@134408 by eter William Green

flavicon
face
so in a nutshell
      _
1/(1-0.9)=infinity

1/infinity=0

therefore
   _
1-0.9 = 0 ?

it's certainly not intuitive but i think it is true.  also seems pretty academic for practical purposes.

it would be interesting to look at this thread (well the rounding thread) from a point of view of how many siginificant digits do i need so that i'm not significantly biasing my calculations ie: my robot won't be off course more than a 1" after traveling 20' using my optical encoder or accelerometer or whatever.

is anybody still reading this thread?  :)

-pete

On Mon, 4 Jun 2001, Jeff DeMaagd wrote:

> {Original Message removed}

2001\06\04@135241 by Dal Wheeler

flavicon
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----- Original Message -----
From: Peter William Green <pwgreen@spam@spamKILLspamENGINEERING.UIOWA.EDU>

> it would be interesting to look at this thread (well the rounding thread)
from a point of view of how many siginificant digits do i need so that i'm
not significantly biasing my calculations ie: my robot won't be off course
more than a 1" after traveling 20' using my optical encoder or accelerometer
or whatever.

Well, that kind of depends on how complex your computations are and how
loose the mechanical tolerances are on your robots (mechanical error vs.
round off error).  --My robots don't need many significant digits at all...
:')

-Dal

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2001\06\04@141942 by Paul Hutchinson

flavicon
face
First, I'd like to thank everyone for their comments on this topic. They
have made me review and re-think the basic concepts of mathematics in
general. I've spent way too much time in the past few days re-reading text
books and searching for other texts on the various fundamental algebraic
operations, definitions and, axioms. However, I don't consider this wasted
time because I firmly believe that blind faith in anything is bad and, I
have not reviewed the fundamentals in the past decade or two.

I especially would like to thank Dave V. for the link to Swarthmore Colleges
excellent Dr. Math project. http://forum.swarthmore.edu/dr.math

There is only one thing I feel comfortable stating with 100% certainty after
my research and review.
If you are a student and the question of, does .999... = 1, comes up on a
test, answer Yes.
I could not find one single reference by any professor/teacher/school
district/college or university that would allow you to answer no and be
given credit for a correct answer. The most complete web resource for info
on this topic I found is,
http://forum.swarthmore.edu/dr.math/faq/faq.0.9999.html. If you read the
page be sure to also read the five linked pages at the end of the FAQ
answer.

> The root problem here appears to be that there some numbers which the
> decimal system is ill equipped to represent, in a manner similar to roman
> numerals having problems with large numbers, only in a deeper manner.
>
> 1/3 is easy to deal with, but can't be represented with complete accuracy
> in decimal form.

This statement has brought much needed closure in my mind as to what the
objections are to the simple algebraic proof I presented in a post last
week. I had been wondering what step(s) in the proof were potentially
flawed. From this statement I see that the disagreement comes with the very
first statement of the proof.
"Given:
 x = 0.9(repeating)"
The problem is that repeating decimals are considered by some to not be
accurate representations of numbers like 1/3. This statement appears to be
somewhat supported by the work of Georg Cantor from the late 19th century.
For 1/3 to be <> 0.333... all that needs to be true is that long division
does not work in some cases. Personally I don't believe this but to my mind
it is certainly possible that at some point in the future this may be proven
to be the case. After all similar events have happened regularly throughout
the course of human history. For those interested I recommend James Burkes,
"The Day the Universe Changed" either the book or television series from the
mid 1980's.

I have decided that in the future if a question regarding repeating decimal
representations of fractions comes up on the PICLIST, I will ask if the
questioner believes that 0.333... = 1/3. If they do I'll try to help but if
they don't I'll ask that the question be restated without the need for
repeating decimals before attempting to help.

Paul

PS - I was a bit shocked by some of the assertions that mathematics is all
magic tricks, I had thought that everyone accepted mathematics as the
official language of science and felt there was no magic to it. I do expect
people to look skeptically at things but to attribute magic to anything is
way more than I can accept.

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2001\06\04@142928 by David VanHorn

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>
>The problem is that repeating decimals are considered by some to not be
>accurate representations of numbers like 1/3. This statement appears to be
>somewhat supported by the work of Georg Cantor from the late 19th century.
>For 1/3 to be <> 0.333... all that needs to be true is that long division
>does not work in some cases.

:) Work it out, and let me know what you get :)
I would assert that it does not work here, since you can't ever finish the
problem.
Feel free to prove me wrong, but show your work. <VBG>

>  Personally I don't believe this but to my mind
>it is certainly possible that at some point in the future this may be proven
>to be the case. After all similar events have happened regularly throughout
>the course of human history. For those interested I recommend James Burkes,
>"The Day the Universe Changed" either the book or television series from the
>mid 1980's.

I'm in agreement here.
Science guides us into theories and systems that are imperfect, but
workable representations of how the universe works. As time progresses, we
refine our theories and systems.


>PS - I was a bit shocked by some of the assertions that mathematics is all
>magic tricks, I had thought that everyone accepted mathematics as the
>official language of science and felt there was no magic to it. I do expect
>people to look skeptically at things but to attribute magic to anything is
>way more than I can accept.

I don't think it's "magic" or anything of the sort. Just a convenient way
to deal with inconvenient numbers.  It works, till something better comes
along.


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2001\06\04@144020 by Paul Hutchinson

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> I don't think it's "magic" or anything of the sort. Just a convenient way
> to deal with inconvenient numbers.  It works, till something better comes
> along.

I'm very sorry, I should have stated that you where completely excluded from
this final comment (since I had mentioned you by name earlier in the post).
I found your arguments to be excellent with absolutely no hints of anything
mystical.

It was some other members who made statements like this including one that
actually said "mathematical manipulation is just card tricks".

Again, sorry for unintentionally implying that you where in that group.

Paul

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2001\06\04@144524 by Byron A Jeff

face picon face
On Sun, Jun 03, 2001 at 11:22:48PM -0400, M. Adam Davis wrote:
>
> Of course, conceptually, 0.999... does not equal one.

Nope. It equals 1. No intents or purposes necessary.

>  It equals
> 0.999....  But using calculus and other methods you see that 0.999...
> approaches 1, and, for all intents and purposes, is equal to 1.  It
> really depends on what level of precision one is asking for.
>  If one
> want infinite precision then one cannot say that 0.999... = 1 unless one
> can prove that 0.999... approaches one faster than the needed precision
> approaches infinity.

Precision implies finiteness. It implies that there will be a cutoff of the
9's at some point in the string.

The 9's end at the same place that the largest possible integer resides. Care
to define that number?

>
> But this is all academic, and is akin to proving that the chicken came
> before the eggroll.  If anyone wants to prove me wrong, then sit down
> and write a 0, a decimal point, an infinite series of nines, and equal
> sign, and a one (no shorthand, please!) before hitting reply.

There's no need for that. The term 0.9 (repeating) is a sufficient
representation for that infinite series. Folks here are failing to grasp that
mathematics for infinity doesn't follow normal finite mathematicl rules.
Equations as simple as 'infinity*2 = infinity' are completely nonsensical
for nonfinite values but true for infinity. Any argument for precision or
truncation of infinity is akin to stating that 'The largest integer is x.'
There's simply to truth to that statement.

In infinity arithmatic 0.9 (repeating) = 1. Not approximates. No approches.
No precision. No error. The proof has been given in this thread multiple times.

I really liked the argument I saw yesterday. I'll repeat it and ask if anyone
can propose a solution: "If 0.9 (repeating) < 1, then there are an infinite
number of real numbers that exists between 0.9 (repeating) and 1. Give one
such number."

And try as you might, you'll find that there is no such number. You'll find
in your search that no matter what number you pick, it will not be between
0.9 (repeating) and 1. Therefore the two values must be the same because not
only can you not define an infinite number of real numbers between the two,
you can't even pick one.

There's no pretense here. Infinity mathematics is exact. Not approximations.
It doesn't exist in the real world, only in the concepts of our minds.

So for the refuters you now need to bring two items to the table. The largest
possible integer, and a number between 0.9 (repeating) and 1.

Good luck.

BAJ

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2001\06\04@174151 by Bill Westfield

face picon face
Heh.  Next we should argue about

       lim     sin(x)/x = 1
       x->0

Lots of signal theory being based on sine waves, this is probably
of more practical application (?)  And it's even less intuitive.

:-)
BillW

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2001\06\04@175626 by Peter L. Peres

picon face
I think that one of the fundamental laws of arithmetics says that a number
is only equal to itself. This includes rational numbers (like 0.(9) and
1). This means that 1 != 0.(9) by definition. Proving this is rather
interesting (i.e. I missed that class). I believe that it can be reduced
to absurdum somehow.

Peter

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2001\06\04@180041 by Jinx

face picon face
> one that actually said "mathematical manipulation is just card tricks"

It wasn't meant to imply any sort of chicanery or mumbo jumbo. David
VanHorn put it better. " I don't think it's "magic" or anything of the sort.
Just a convenient way to deal with inconvenient numbers.  It works, till
something better comes along". It's just how these convoluted means
to an end look to a mathematical outsider

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2001\06\04@185516 by Bill Westfield

face picon face
   I think that one of the fundamental laws of arithmetics says that a number
   is only equal to itself. This includes rational numbers (like 0.(9) and
   1). This means that 1 != 0.(9) by definition.

But ".999 repeating" is not a "number", per se.  It's shorthand for an
algorithm that produces a value (that happens to be 1.0)

BillW

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2001\06\04@195048 by Russell McMahon

picon face
> 'Snot what I said.
> 1/3 is a precise representation, 0.3333 isn't
> PI works, 3.141... isn't precise.

Full circle!!! :-)
This is where this topic started.

Pi to 4 significant figures / 2 decimal places should be 3.142 as hammered
out in brain burp rounding.
(But I know you knew that and it wasn't the point you were making)

Quite coincidentally, Pi for most any engineering purpose is 355/113
High by about 0.00000026676...
Easy to remember 113355 and split it in two and divide.
Courtesy HP long ago.



           Russell McMahon

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2001\06\04@201839 by michael brown

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> Easy to remember 113355 and split it in two and divide.
> Courtesy HP long ago.
>
OH NO another thing to remember. ;-D  I'll pass on this and continue
recalling what I already learned about pi.  3.1415926585 (PS I didn't cheat,
this is off the top of my head. So I could be wrong!)  If I ever need more
precision than this I will just look it up. ;-D  I doubt that I ever will,
since this is more than accurate enough to navigate to the moon should I
ever build a Pic controlled spacecraft.  Thanks everyone! It's been fun.  I
love a good argument.  I'm still not convinced though.  TTYL

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2001\06\04@203601 by Bob Barr

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Russell McMahon wrote:

<snip>

>Quite coincidentally, Pi for most any engineering purpose is 355/113
>High by about 0.00000026676...
>Easy to remember 113355 and split it in two and divide.
>Courtesy HP long ago.
>
>
Depending on the accuracy required, 22/7 can work also. While not as
accurate as 355/113, it's only high by about 0.001264489... (about 0.04%). I
find the 22/7 easier to remember. :=)
Courtesy of a Forth Interest Group member, also long ago.


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2001\06\05@014016 by Bill Westfield

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   I'll pass on this and continue recalling what I already learned
   about pi.  3.1415926585 (PS I didn't cheat, this is off the top
   of my head. So I could be wrong!)

My memory says 3.14159265*3*5...  (hmm.  Found at least one
online source that agrees with me (and another that says "42"))

BillW

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2001\06\05@015521 by David VanHorn

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>
>My memory says 3.14159265*3*5...  (hmm.  Found at least one
>online source that agrees with me (and another that says "42"))

The indiana legislature nearly passed a law defining it as 3.2

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