# [Maxima] integrate returns undefined

Richard Hennessy rvh2007 at comcast.net
Wed Sep 10 10:31:20 CDT 2008

```Sorry, I missed the corect answer.  I just thought of this.

solve (sin(x-y)/(x-y)=0,x);
[x=y+%pi]

Rich

----- Original Message -----
From: "Richard Hennessy" <rvh2007 at comcast.net>
To: <fateman at cs.berkeley.edu>
Cc: <maxima at math.utexas.edu>
Sent: Wednesday, September 10, 2008 11:23 AM
Subject: Re: [Maxima] integrate returns undefined

> Rich,
>
> Automatic taking of limits is not always the answer for many people.
> Personnally I would like this feature
> (%i1) solve (sin(x-y)/(x-y)=0,x);
> (%o1) []
>
> since I think a "solution" that makes the demominator zero is never
> "right".
>
> Rich
>
>
> ----- Original Message -----
> From: "Richard Fateman" <fateman at cs.berkeley.edu>
> To: "'Richard Hennessy'" <rvh2007 at comcast.net>
> Cc: <maxima at math.utexas.edu>
> Sent: Wednesday, September 10, 2008 11:04 AM
> Subject: RE: [Maxima] integrate returns undefined
>
>
>> Your saying that something is not a bug does not mean everyone will agree
>> with you.
>> Or even that it will result in non-buggy results.  Many "bugs" reported
>> on
>> sci.math.symbolic
>> by one writer as bugs in "integrate"  in Maple, are bugs in
>> simplification,
>> sometimes
>> just like this "obvious" but sometimes wrong feature.
>>
>> In particular, you may not need reminding about a=0 in this case, but
>> what
>> in other cases, where Maxima just goes ahead without you... e.g.
>> solve (sin(x-y)/(x-y)=0,x)
>>
>> returns x=y;
>> but this is not a solution, which can be seen either by direct
>> substitution
>> or
>> taking a limit.
>>
>> RJF
>>
>>
>>
>>
>>
>>
>>
>>> -----Original Message-----
>>> From: Richard Hennessy [mailto:rvh2007 at comcast.net]
>>> Sent: Wednesday, September 10, 2008 7:26 AM
>>> To: fateman at EECS.Berkeley.EDU; 'John Pye'; maxima at math.utexas.edu
>>> Cc: 'Edwin Woollett'
>>> Subject: Re: [Maxima] integrate returns undefined
>>>
>>> This is not a bug, this simplifies to 1
>>>
>>> a/a -> 1
>>>
>>> with no assumptions made.  I have noticed that in general
>>> radcan(expr1/expr1) simplifies to 1 and Maxima never says
>>> except when expr1
>>> = 0.  Which I find useful since I know about the possibility
>>> that expr1
>>> could be zero but I don't really need to be reminded of this case.  I
>>> definitely would not want to be asked is expr1 = zero all the
>>> sime when
>>> cancelling terms.  That would be annoying.
>>>
>>> Rich
>>>
>>>
>>> ----- Original Message -----
>>> From: "Richard Fateman" <fateman at cs.berkeley.edu>
>>> To: "'John Pye'" <john.pye at anu.edu.au>; <maxima at math.utexas.edu>
>>> Cc: "'Edwin Woollett'" <woollett at charter.net>
>>> Sent: Tuesday, September 09, 2008 11:56 PM
>>> Subject: Re: [Maxima] integrate returns undefined
>>>
>>>
>>> > Not so clear a bug.
>>> > (n-m)/(n-m) simplifies to 1.
>>> > But if you know n=m, then you have 0/0.  So is it a bug if
>>> (n-m)/(n-m) -->
>>> > 1?
>>> >
>>> > Answer: maybe. But not clear :)
>>> >
>>> > RJF
>>> >
>>> >
>>> >> -----Original Message-----
>>> >> From: maxima-bounces at math.utexas.edu
>>> >> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of John Pye
>>> >> Sent: Tuesday, September 09, 2008 6:47 PM
>>> >> To: maxima at math.utexas.edu
>>> >> Cc: Edwin Woollett
>>> >> Subject: Re: [Maxima] integrate returns undefined
>>> >>
>>> >> I can confirm that behaviour; it looks like a clear bug to me.
>>> >>
>>> >> Cheers
>>> >> JP
>>> >>
>>> >> Edwin Woollett wrote:
>>> >> > integrate(..) returns undefined when it
>>> >> > should know the answer.
>>> >> >
>>> >> > (%i1) declare( [ m, n ], integer )\$
>>> >> > (%i2) assume ( m > 0,  n > 0 )\$
>>> >> > (%i3) integrate( cos(m*x)^2, x, 0, 2*%pi );
>>> >> > (%o3)                                 %pi
>>> >> > (%i4) integrate( cos(m*x)*cos(n*x), x, 0, 2*%pi  );
>>> >> > Is  n - m  positive, negative, or zero?
>>> >> >
>>> >> > zero;
>>> >> > (%o4)                              undefined
>>> >> >
>>> >> > Is this a known bug?
>>> >>
>>> >> _______________________________________________
>>> >> Maxima mailing list
>>> >> Maxima at math.utexas.edu
>>> >> http://www.math.utexas.edu/mailman/listinfo/maxima
>>> >>
>>> >
>>> > _______________________________________________
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>>>
>>>
>>
>
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