Problem with integrate() (was: Re: What am I doing wrong with this cycle?)
Subject: Problem with integrate() (was: Re: What am I doing wrong with this cycle?)
From: Stavros Macrakis
Date: Thu, 18 Jul 2013 15:20:10 -0400
That sounds consistent with my hypothesis about the problem.
On Thu, Jul 18, 2013 at 2:18 PM, Pyotr Ivanshin <pivanshin at gmail.com> wrote:
> Well, thanks for your kind cooperation.
>
> The configuration is
>
> maxima 5.28.0-2 on Windows 7
>
> Actually the computation goes wrong only in the loop. If I do the
> operations manually (step by step), everything is OK. So there seems to be
> no problem with integration itself.
>
> The loop does it.
>
> For example in this case
>
> f[1](z, t)=-2*((rw5*z^(k+1))/(k+1)+rw5*t^k*z) instead of
> -20*((rw5*z^(k+1)*t)/(k+1)+
> rw5*t^(k+1)*z/(k+1))
>
> It seems that the program applies operation corresponding to the letter
> "c" and completely forgets "d".
>
> Later on it still keeps on integrating by z and works some miracles with
> the multiplier before the brackets.
>
> f[2](z,t)=2*((rw5*z^(k+2))/((k+1)*(k+2))+(rw5*t^k*z^2)/2)
>
> f[3](z,t)=-(rw5*z^(k+3))/((k+1)*(k+2)*(k+3))-(rw5*t^k*z^3)/6
>
>
>
>
>
> 2013/7/18 Stavros Macrakis <macrakis at alum.mit.edu>
>
>> Could you tell us what configuration you're running in? Use bug_report()
>> to get the info.
>>
>> Thanks,
>>
>> -s
>>
>>
>> On Thu, Jul 18, 2013 at 12:22 PM, Przemek Klosowski <
>> przemek.klosowski at nist.gov> wrote:
>>
>>> Recently, Pyotr Ivanishin asked for help and it seems that his troubles
>>> result from the following problem with integrate():
>>>
>>> integrate(x^k,x);
>>> Is k + 1 zero or nonzero?
>>>
>>> nonzero;
>>> (%o15) log(x)
>>> (%i16) integrate(x^k,x);
>>> Is k + 1 zero or nonzero?
>>>
>>> zero;
>>> (%o16) log(x)
>>>
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>>
>>
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>