> Windows Calc informs me that the answer is 2, which is definitely
> unexpected.
>
> My mobile (Android) gives a different answer to my Casio. The phone gives
> the same answer as an Acorn Archimedes running BBC Basic.
>
> Colin
> --
> cdb, EraseMEcolinspam_OUTTakeThisOuTbtech-online.co.uk on 11/03/2012
>
> Web presence: http://www.btech-online.co.uk
>
> Hosted by:  http://www.justhost.com.au
>
>
> This email is to be considered private if addressed to a named  individual
> or Personnel Department, and public if addressed to a blog,  forum or news
> article.
>
>
>
>

> On Sun, 11 Mar 2012 01:41:41 +0200, Chris Roper wrote:
> :: Now I have lost faith in my favorite calculator, I get the wrong
> :: answer either way.
>
> Well I suppose it all depends on whether brackets take precedence over
> operators.
>
> Colin
> --
> cdb, KILLspamcolinKILLspambtech-online.co.uk on 11/03/2012
>
> Web presence: http://www.btech-online.co.uk
>
> Hosted by:  http://www.justhost.com.au
>
>
> This email is to be considered private if addressed to a named  individual
> or Personnel Department, and public if addressed to a blog,  forum or news
> article.
>
>
>
>
>
>

> On Sun, 11 Mar 2012, cdb wrote:
>
>> I saw this on an RISCOS enthusiast website.
>>
>> Using, head, as many different calculators that you have to hand
>> (especially if you have an iPhone or Windows calc) what result do you get
>> from the following sum.
>>
>> 6/2(1+2)
>>
>> Type it in exactly as above.
>>
>> My trusty Casio fx5000f  let me down, sort of.
>>
>> Colin
>> --
>> cdb,  on 11/03/2012
>>
> Any of the calculators I have with any sort of algebraic ordering come up
> with the result of 9.
>
> The RPN calculators agree with Dwayne with a result of 1.
>
> I have "several" calculators.......
>
> Jamie

> ...I wasn't specifically thinking about RPN when I typed that.
>
> Does'nt that explain the discrepancies? The notation is imprecise,
> thus the differing interpretations by operators <and> the Deus Ex
> Machina who programmed the calculator.
>
> The more I think about it, the more "Syntax Error" seems the correct
> answer. I've rarely seen recommendations for other than explicit ex-
> pressions in pgming manuals - Other than C, of course...  :)
>
> Jack
> --

> Dwayne Reid <RemoveMEdwaynerspam_OUTKILLspamplanet.eon.net> writes:
>> Regardless, I fall upon the old mnemonic phrase for order of math
>> operations that my Maths teacher gave to me way back in grade school:
>> BOMDAS = Brackets, then Odd_Functions, then Multiply, then Divide,
>> then Add, then Subtract.
>
> This is amusing to read. In the UK, at least, school students are taught
> "BODMAS" (where "O" stands for "Other", if I recall correctly). Of
> course, since division is just multiplication combined with a (tighter
> binding) reciprocal, it shouldn't matter.
>
> The problem is that it's hard to know how to make sense of
>
>  1/2/3
>
> (as a pair of quotients, rather than a date, which has its own
> problems!)
>
> This doesn't come from problems of operator precedence, but rather from
> the fact that "/" isn't associative. Fortunately, people make things
> much more obvious when scribbling on paper.
>
> I should say, my immediate interpretation of the above is (1/2)/3, but
> I've spent a significant fraction of my life able to program in C, so I
> suspect that C/Algol/whatever's heritage has more influence on me than
> anything mathematical.
>
> Similar problems arise with 1 - 2 - 3, of course. But (since subtraction
> is always written in one dimension?), the (1-2)-3 interpretation seems
> pretty much universal.
>
>
> Rupert
>

> In elementary school (US) I was taught: PEMDAS = Please Excuse My Dear
> Aunt Sally
>
> or
>
> Parentheses
> Exponents
> Multiplication
> Division
> Addition
> Subtraction
>
> Although, I think this is misleading at best. For example, it suggests
> that addition should precede subtraction, as in:
>
> 3-2+4 would be 3-(2+4) rather than (3-2)+4. As others have pointed
> out, this has to do with association and not order of operations.
>
> Sean

> On Sun, 11 Mar 2012 15:45:05 +1300, RussellMc wrote:
> :: Reverse the order of the two indivisible* portions.
> :: A = (1 + 2) * 6 / 2
>
> Yes, but,ignoring RPN for a moment, surely the 'convention' is that a
> bracketed sum is performed first and then depending on the incarnation (of
> compiler) the next sequence would be to read the remaining operators with
> the same precedence in left to right order.
>
> In which case as my trusty Casio states, the answer is 1, only if the
> division is performed first does the result come to 9 as per other
> algorithms.
>
> Colin
> --
> cdb, EraseMEcolinspamspamBeGonebtech-online.co.uk on 11/03/2012
>
> Web presence: http://www.btech-online.co.uk
>
> Hosted by:  http://www.justhost.com.au
>
>
> This email is to be considered private if addressed to a named  individual
> or Personnel Department, and public if addressed to a blog,  forum or news
> article.
>
>
>
>
>
>

> Whenever I use a calculator (or a compiler) I sprinkle brackets
> everywhere. It usually annoys someone but it saves me in the long run.
>
> On 3/10/2012 10:42 PM, cdb wrote:
>> On Sun, 11 Mar 2012 15:45:05 +1300, RussellMc wrote:
>> :: Reverse the order of the two indivisible* portions.
>> :: A = (1 + 2) * 6 / 2
>>
>> Yes, but,ignoring RPN for a moment, surely the 'convention' is that a
>> bracketed sum is performed first and then depending on the incarnation (of
>> compiler) the next sequence would be to read the remaining operators with
>> the same precedence in left to right order.
>>
>> In which case as my trusty Casio states, the answer is 1, only if the
>> division is performed first does the result come to 9 as per other
>> algorithms.
>>
>> Colin
>> --
>> cdb, RemoveMEcolinKILLspambtech-online.co.uk on 11/03/2012
>>
>> Web presence: http://www.btech-online.co.uk
>>
>> Hosted by:  http://www.justhost.com.au
>>
>>
>> This email is to be considered private if addressed to a named  individual
>> or Personnel Department, and public if addressed to a blog,  forum or news
>> article.
>>
>>
>>
>>
>>

> I hate how GCC "suggests" adding parenthesis around mixed operators with
> "ambiguous" precedence, and also for ambiguous if/else.
> It turns out that there's nothing ambiguous in the operator precedence
> or if/else in C.
>
> For instance:
>
> if( a )
>     if( b )
>         ...
>     else
>         ...
>
> It's obvious that the "else" belongs to the second "if", but GCC issues
> a warning. Annoying.
>
> And:
>
> if( expr1 && expr2 || expr3 && expr4 )
>      ...
>
> Also gives a warning.
>
>
> Perhaps the compiler developers fear they may have made some mistake and
> ask the programmers to add parenthesis to avoid exposing a bug in the
> compiler?
>
>
> Isaac
>

> I have a colleague who insists on using this reverse syntax
>
> if(0 == x) {
> ...do stuff
> }
>
> which I find odd to read at the best of times...
>
> We're using embedded C, (Hitech), and whilst
> if(x =0)   doesn't throw an error, it does throw a warning.
>
> oh well.
>
> -Jim
>
>
> >
> >
> >
> > Isn't that just what warnings are for? It compiles OK but it might not be
> > what you wanted. Just like:
> >
> > if (A=B){
> > ...
> >
>
>
>
>

>
> On 12 March 2012 10:03, Jim <@spam@jimf@spam@spam_OUTwebstudios.co.uk> wrote:
>
> > I have a colleague who insists on using this reverse syntax
> >
> > if(0 == x) {
> > ...do stuff
> > }
> >
> > which I find odd to read at the best of times...
> >
> > We're using embedded C, (Hitech), and whilst
> > if(x =0)   doesn't throw an error, it does throw a warning.
> >
> > oh well.
> >
> > -Jim
> >
> >
> > >
> > >
> > >
> > > Isn't that just what warnings are for? It compiles OK but it might not
> be
> > > what you wanted. Just like:
> > >
> > > if (A=B){
> > > ...
> > >
> >
> >
> >
> >

> On 12 March 2012 09:20, Chris Roper caroper@gma
> il.com> wrote:
> > I agree with your colleague.
> > I use several compilers and several "C Type"
> languages, not all of them> will give a warning but all will generate the
> error.>
>
> You mean if you write:
>
> if ( 0 = x ) ...
>
> then not all C compiler will generate an error?
>
> Tamas
>
>
>
>
> >
> > On 12 March 2012 10:03, Jim jimf@we
> bstudios.co.uk> wrote:>
> > > I have a colleague who insists on using this
> reverse syntax> >
> > > if(0 == x) {
> > > ...do stuff
> > > }
> > >
> > > which I find odd to read at the best of
> times...> >
> > > We're using embedded C, (Hitech), and
> whilst> > if(x =0)   doesn't throw an error, it does throw
> a warning.> >
> > > oh well.
> > >
> > > -Jim
> > >
> > >
> > > >
> > > >
> > > >
> > > > Isn't that just what warnings are for? It
> compiles OK but it might not> be
> > > > what you wanted. Just like:
> > > >
> > > > if (A=B){
> > > > ...
> > > >
> > >
> > >
> > >
> > >
> > > --

> Using this example:-
>
> if(iBlock_Size = 0)
> {
>    return 0;
> }
> gives this:-
> Warning [758] C:\Source\UI_Test\dongle.c; 107. constant conditional branch: possible use of "=" instead of "=="
>
> BUT still builds ok..
>
> obviously the syntax should be
>
> if(iBlock_Size == 0)
> {
>    return 0;
> }
>
> but my colleague uses
> if(0 == iBlock_Size)
> {
>    return 0;
> }
>
> Which although syntactically correct, just doesn't feel right.
> He uses it for ALL ifs  so
> if(127 < iBlock_Size)
> {
>    return 0;
> }
>
> Which is counter intuitive in my mind. Perhaps I am just getting old?
>
> They should ALL produce an error with
> if(0 = iBlock_Size)
> {
>    return 0;
> }
> as you cannot assign to the 0 on the left side
> Error   [202] C:\Source\UI_Test\dongle.c; 107.19 only lvalues may be assigned to or modified
>
>
>
>
> On Mon 12/03/12 10:18 AM , Tamas Rudnai TakeThisOuTtamas.rudnai.....TakeThisOuTgmail.com sent:
>> On 12 March 2012 09:20, Chris Roper caroper@gma
>> il.com> wrote:
>> > I agree with your colleague.
>> > I use several compilers and several "C Type"
>> languages, not all of them> will give a warning but all will generate the
>> error.>
>>
>> You mean if you write:
>>
>> if ( 0 = x ) ...
>>
>> then not all C compiler will generate an error?
>>
>> Tamas
>>
>>
>>
>>
>> >
>> > On 12 March 2012 10:03, Jim jimf@we
>> bstudios.co.uk> wrote:>
>> > > I have a colleague who insists on using this
>> reverse syntax> >
>> > > if(0 == x) {
>> > > ...do stuff
>> > > }
>> > >
>> > > which I find odd to read at the best of
>> times...> >
>> > > We're using embedded C, (Hitech), and
>> whilst> > if(x =0)   doesn't throw an error, it does throw
>> a warning.> >
>> > > oh well.
>> > >
>> > > -Jim
>> > >
>> > >
>> > > >
>> > > >
>> > > >
>> > > > Isn't that just what warnings are for? It
>> compiles OK but it might not> be
>> > > > what you wanted. Just like:
>> > > >
>> > > > if (A=B){
>> > > > ...
>> > > >
>> > >
>> > >
>> > >
>> > >
>> > > --

> On 12 March 2012 09:20, Chris Roper <RemoveMEcaroperspamBeGonegmail.com> wrote:
>
> > I agree with your colleague.
> > I use several compilers and several "C Type" languages, not all of them
> > will give a warning but all will generate the error.
> >
>
> You mean if you write:
>
> if ( 0 = x ) ...
>
> then not all C compiler will generate an error?
>
> Tamas
>
>
>
>
> >
> > On 12 March 2012 10:03, Jim <spamBeGonejimf@spam@spam_OUTwebstudios.co.uk> wrote:
> >
> > > I have a colleague who insists on using this reverse syntax
> > >
> > > if(0 == x) {
> > > ...do stuff
> > > }
> > >
> > > which I find odd to read at the best of times...
> > >
> > > We're using embedded C, (Hitech), and whilst
> > > if(x =0)   doesn't throw an error, it does throw a warning.
> > >
> > > oh well.
> > >
> > > -Jim
> > >
> > >
> > > >
> > > >
> > > >
> > > > Isn't that just what warnings are for? It compiles OK but it might
> not
> > be
> > > > what you wanted. Just like:
> > > >
> > > > if (A=B){
> > > > ...
> > > >
> > >
> > >
> > >
> > >
> > > --

> > I have a colleague who insists on using this
> reverse syntax>
> > if(0 == x) {
> > ...do stuff
> > }
> >
> > which I find odd to read at the best of
> times...>
> > We're using embedded C, (Hitech), and
> whilst> if(x =0)   doesn't throw an error, it does throw a
> warning.>
> > oh well.
>
> The reason for using the
>
> If (0 == x) {...
>
> is to throw an error if one of the = signs is accidently left out giving an
> assignment instead of an equality.
> It may well be that
> if (x = 0) {...
> is meant to be correct code (unlikely) but is more of a problem if the code
> is supposed to be if (x = b) {...
>
> i.e. you mean to do the assignment, but the if() statement is looking at
> the value of b to see if the statement should be executed - obfuscated code
> forever ...--
> Scanned by iCritical.
>

>
>
> On 12/03/2012 11.41, Tamas Rudnai wrote:
> >
> > I am still having a trouble to remember what I have learned in school (as
> > opposed to what I am applying nowadays), but all my braincells tells me
> > that division and multiplication has the very same priority and should be
> > handled from left to right.
> >
> > Therefore 6 / 2 * (1 + 2 ) should be
> >
> > 6
> > -- * (1+2) = 9
> > 2
> I remember very well what lerned at school and this is the only right
> interpretation.
> And is simple and smart!
> When writing by hand it's correct to omit the * because this is in The
> Rule.
>
> With any programming language we must see The Rule on operator precedence
> but I
> think that if it came out with something different it can be wrong (may
> exists a
> contest in which...).
>
>
>

> -----Original Message-----
> From: @spam@piclist-bouncesspam_OUT.....mit.edu [spamBeGonepiclist-bouncesEraseMEmit.edu] On Behalf
> Of RussellMc
> Sent: 13 March 2012 14:53
> To: Microcontroller discussion list - Public.
> Subject: Re: [OT] Maths fun
>
> > Nonsense,
>
> ?
>
> > the answer should be according to the rules of the system at
> > hand! If a system does not adhere to its own rules it is wrong, but when
> > it has strange rules it is just strange.
>
> I am saying that the answer to
>
>     6/2 * (1+2)
>
> as written, and based on the "proper" [tm] rules of mathematics = 9.
> I am saying that "1" is an incorrect answer.
> Do you disagree in either case?
>
> If you do disagree, do you hold that " * " is not commutative?
> Or ... ?
>
> Is:
>
> 6/2 * (1+2)  = =  (1+2) * 6/2 ?
>
>

> -----Original Message-----
> From: piclist-bouncesspamBeGonemit.edu [RemoveMEpiclist-bounces@spam@spamBeGonemit.edu] On Behalf
> Of RussellMc
> Sent: 13 March 2012 14:53
> To: Microcontroller discussion list - Public.
> Subject: Re: [OT] Maths fun
>
> > Nonsense,
>
> ?
>
> > the answer should be according to the rules of the system at
> > hand! If a system does not adhere to its own rules it is wrong, but when
> > it has strange rules it is just strange.
>
> I am saying that the answer to
>
>     6/2 * (1+2)
>
> as written, and based on the "proper" [tm] rules of mathematics = 9.
> I am saying that "1" is an incorrect answer.
> Do you disagree in either case?
>
> If you do disagree, do you hold that " * " is not commutative?
> Or ... ?
>
> Is:
>
> 6/2 * (1+2)  = =  (1+2) * 6/2 ?
>
>

>
> APL btw evaluates strictly from right to left!
>
> --
>
> Wouter van Ooijen
>
> -- -------------------------------------------
> Van Ooijen Technische Informatica: http://www.voti.nl
> consultancy, development, PICmicro products
> docent Hogeschool van Utrecht: http://www.voti.nl/hvu
> C++ on uC blog: http://www.voti.nl/erblog
>

> Here we are - the website that originally started all this off 9(or those
> looking for a proper maths teacher :) ).
>
> http://www.pilearn.com/
>
> Warning, people who enter, might be gone some time.
>
> Colin
> --
> cdb, spamBeGonecolinKILLspam@spam@btech-online.co.uk on 14/03/2012
>
> Web presence: http://www.btech-online.co.uk
>
> Hosted by:  http://www.justhost.com.au
>
>
> This email is to be considered private if addressed to a named  individual
> or Personnel Department, and public if addressed to a blog,  forum or news
> article.
>
>
>
>