Subject: double integrals seem to give different answers
From: Richard Hennessy
Date: Sun, 22 Nov 2009 13:19:04 -0500
I think it may be a root choice, I am not really sure. Try plotting these.
The abs(rho) term could come from a root assumption that chooses positive
answers. Which is fine, I like that. Anyway trigsimp, trigreduce and
trigrat do not all agree. Try...
ans:[f(x,y,z)*J,trigsimp(f(x,y,z)*J),trigreduce(f(x,y,z)*J),trigrat(f(x,y,z)*J)]$
plot2d(ans,[rho,-1,1]),theta=0,phi=%pi/3;
plot2d(ans,[rho,-1,1]),theta=1,phi=%pi/5;
Rich
--------------------------------------------------
From: "G. Jay Kerns" <gkerns at ysu.edu>
Sent: Sunday, November 22, 2009 11:30 AM
To: "Leo Butler" <l.butler at ed.ac.uk>
Cc: "Richard Fateman" <fateman at cs.berkeley.edu>; "Maxima List"
<maxima at math.utexas.edu>
Subject: Re: [Maxima] double integrals seem to give different answers
> Dear Leo,
>
> On Sun, Nov 22, 2009 at 4:37 AM, Leo Butler <l.butler at ed.ac.uk> wrote:
>> Just to be clear, this is not the root of the error for this integral.
>> You can verify that by declaring
>>
>> assume(rho >= 0);
>>
>> and computing the two integrals.
>>
>> Leo
>>
>> --
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
>
> Thanks for the remarks, but no, for the record, different answers are
> returned (on my system, at least) even with
>
> assume(rho >= 0);
>
> I am running i-386 Debian sid with the below Maxima version info. I
> also observe this on Ubuntu 9.10 amd64.
>
> Regards,
> Jay
>
>
> Maxima 5.19.2 http://maxima.sourceforge.net
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>
>
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> Associate Professor
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