[Maxima] wrong symbolic sum

Robert Dodier robert.dodier at gmail.com
Sun Jul 26 10:57:53 CDT 2009

On 7/26/09, Barton Willis <willisb at unk.edu> wrote:

> With CVS Maxima, the results are different:
>  (%i18) sum(-k, k, -a, -1), simpsum, factor;
>  (%o18) a*(a+1)/2

OK, that's good news, glad to see the bug was fixed somehow.

> Manifestly empty sums simplify to zero:
>  (%i19) sum(-k,k,5,-1);
>  (%o19) 0
> I suggest that we consider restoring the sumhack option.

OK by me to restore sumhack. (I'm the one who cut it out in a
larger revision of the summation code in 2005. I think I was
acting on a suggestion from someone else, although I can't
find a record of it at the moment.)

If we want to be very careful, the symbolic result should respect
sumhack as well. I don't know if it's worth the trouble.


Robert Dodier

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