This seems to be a bug introduced by recent changes to %piargs:
(%i1)
integrate(cos(x)-cos(x-c),x,0,c/2)=%pi-c-integrate(cos(x-c),x,c,%pi/2+c);
Is c positive, negative, or zero? pos;
(%o1) 2*sin(c/2)-sin(c)=-c+sin((4*%pi*false-%pi)/2)-sin(2*%pi*false)+%pi
(%i2) %piargs : false$
(%i3)
integrate(cos(x)-cos(x-c),x,0,c/2)=%pi-c-integrate(cos(x-c),x,c,%pi/2+c);
Is c positive, negative, or zero? pos;
(%o3) -sin(c)+2*sin(c/2)-sin(0)=-c-sin(%pi/2)+sin(0)+%pi
Barton
-----maxima-bounces at math.utexas.edu wrote: -----
>To: maxima at math.utexas.edu
>From: "'Milan Lukic'" <milan at eskimo.com>
>Sent by: maxima-bounces at math.utexas.edu
>Date: 08/20/2007 11:47AM
>Subject: Re: [Maxima] An integration question
>
>Thank you Richard and Stavros. Since this bug seem to be introduced
>after Maxima 5.12, I suspect that instead of filling a bug report, it
>would be better to fix the problem before releasing 5.13.
>
>Milan
>
>* Richard Fateman <fateman at cs.berkeley.edu> [2007-08-20 09:43:05
>-0700]:
>
>> Clearly this is a bug.
>>
>> -----Original Message-----
>> From: maxima-bounces at math.utexas.edu
>[mailto:maxima-bounces at math.utexas.edu]
>> On Behalf Of Milan Lukic
>> Sent: Monday, August 20, 2007 9:29 AM
>> To: maxima at math.utexas.edu
>> Subject: An integration question
>>
>> I don't understand how/why Maxima returns the following:
>>
>> (%i3)
>>
>integrate(cos(x)-cos(x-c),x,0,c/2)=%pi-c-integrate(cos(x-c),x,c,%pi/2+c);
>> Is c positive, negative, or zero?
>>
>> pos;
>> (%o3) 2*sin(c/2)-sin(c) =
>-c+sin((4*%pi*false-%pi)/2)-sin(2*%pi*false)+%pi
>>
>> What is this "false" doing in the answer? In case it plays any role,
>> here is the build_info:
>>
>>
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