Exact match. Not showing close matches.
PICList
Thread
'[OT] Mathematical question'
1999\12\05@022211
by
Quentin
This might seem waaay OT but there is a PIC in there somewhere.
Can somebody please help this rusted brain:
I've been given information as such:
if x=0, y=0
x=15, y=0.259
30, 0.5
45, 0.707
60, 0.866
75, 0.966
90, 1.000
You will see that while X is linear, Y is not (Log??). With these
information available, how would I calculate Y for all the other values
of X?
I want to use it in a lookup table in the PIC.
Thanks
Quentin
1999\12\05@025156
by
Russell McMahon

Quentin,
What you want depends on whether your question is specific or general and
how accurate you want the result.
What you have described is the results for Y = Sin(X)
X in degrees.
You can calculate this using a Sin function.
If you are using assembler such routines are available.
If you are using C or BASIC or some other high level language then the
function is (probably) already available in the language.
If this is a general question then the normal method is "interpolation".
Linear interpolation is the simplest form of this and generally the least
accurate but may be OK for your purpose.
Before we go into this it would be useful for you to provide some more
information eg
 Are you after Sin (as shown here) or is the question more general?
 What accuracy do you need?
 What is the application?
regards
Russell McMahon
_____________________________
>From other worlds  http://www.easttimor.com
http://www.sudan.com
What can one man* do?
Help the hungry at no cost to yourself!
at http://www.thehungersite.com/
(*  or woman, child or internet enabled intelligent entity :))
From: Quentin <spam_OUTqscTakeThisOuTICON.CO.ZA>
{Quote hidden}>This might seem waaay OT but there is a PIC in there somewhere.
>Can somebody please help this rusted brain:
>
>I've been given information as such:
>if x=0, y=0
>x=15, y=0.259
>30, 0.5
>45, 0.707
>60, 0.866
>75, 0.966
>90, 1.000
>
>You will see that while X is linear, Y is not (Log??). With these
>information available, how would I calculate Y for all the other values
>of X?
>
>I want to use it in a lookup table in the PIC.
1999\12\05@031323
by
Harold Hallikainen

On Sun, 5 Dec 1999 09:24:25 +0200 Quentin <.....qscKILLspam@spam@ICON.CO.ZA> writes:
>This might seem waaay OT but there is a PIC in there somewhere.
>Can somebody please help this rusted brain:
>
>I've been given information as such:
>if x=0, y=0
>x=15, y=0.259
>30, 0.5
>45, 0.707
>60, 0.866
>75, 0.966
>90, 1.000
>
>You will see that while X is linear, Y is not (Log??). With these
>information available, how would I calculate Y for all the other
>values
>of X?
>
>I want to use it in a lookup table in the PIC.
Well, I HAVE done a 7th order power series by solving 7 equations with 7
unknowns (the coefficients). It worked, but was a lot of trouble.
Last time, I used a standard curve fitting program (Curve Expert). Jack
Crenshaw mentions a bunch of them in the December issue of Embedded
Systems Programming. Here are the ones he lists:
http://www.micromath.com/scientist.html
http://www.spss.com
http://www.ebicom.net/~dhyams/cvxpt.htm
Harold
___________________________________________________________________
Why pay more to get Web access?
Try Juno for FREE  then it's just $9.95/month if you act NOW!
Get your free software today: dl.http://www.juno.com/dynoget/tagj.
1999\12\05@075715
by
andy howard
> This might seem waaay OT but there is a PIC in there somewhere.
> Can somebody please help this rusted brain:
> I've been given information as such:
> if x=0, y=0
> x=15, y=0.259
> 30, 0.5
> 45, 0.707
> 60, 0.866
> 75, 0.966
> 90, 1.000
> You will see that while X is linear, Y is not (Log??). With these
> information available, how would I calculate Y for all the other values
> of X?
This is a sine function. Y = sin(X). You can do it on your calculator or
look it up in a book of tables.
> I want to use it in a lookup table in the PIC.
Somewhere I've seen a application that does exactly this to generate a
pseudosine wave for audio testing. If I can find it I'll post a pointer.
.
1999\12\06@001815
by
Joseph Rutsky
This is the sin function.
Quentin wrote:
{Quote hidden}> This might seem waaay OT but there is a PIC in there somewhere.
> Can somebody please help this rusted brain:
>
> I've been given information as such:
> if x=0, y=0
> x=15, y=0.259
> 30, 0.5
> 45, 0.707
> 60, 0.866
> 75, 0.966
> 90, 1.000
>
> You will see that while X is linear, Y is not (Log??). With these
> information available, how would I calculate Y for all the other values
> of X?
>
> I want to use it in a lookup table in the PIC.
>
> Thanks
> Quentin
1999\12\06@030135
by
Dr. Imre Bartfai
Hi,
the equation is: y = sin(x)
I hope this helps.
Imre
On Sun, 5 Dec 1999, Quentin wrote:
{Quote hidden}> This might seem waaay OT but there is a PIC in there somewhere.
> Can somebody please help this rusted brain:
>
> I've been given information as such:
> if x=0, y=0
> x=15, y=0.259
> 30, 0.5
> 45, 0.707
> 60, 0.866
> 75, 0.966
> 90, 1.000
>
> You will see that while X is linear, Y is not (Log??). With these
> information available, how would I calculate Y for all the other values
> of X?
>
> I want to use it in a lookup table in the PIC.
>
> Thanks
> Quentin
>
>
1999\12\06@055851
by
Quentin
Thanks All
Told you my brain is rusted.
Quentin
More... (looser matching)
 Last day of these posts
 In 1999
, 2000 only
 Today
 New search...