[Maxima] simplify_sum error

[Raymond Toy]

On Tue, Mar 13, 2012 at 12:35 AM, Andrej Vodopivec <
andrej.vodopivec at gmail.com> wrote:

>
> simplify_sum finds that this sum equals 2/3*hypergeometric([-1/2,
> 3/4],[7/4],-1). The error comes from hgfred:
>
> (%i1) 2/3*hgfred([-1/2,3/4],[7/4],-1);
> expt: undefined: 0 to a negative exponent.
>  -- an error. To debug this try: debugmode(true);
>

Curious.  I was getting this error too.  But then I went and recompiled
src/hyp.lisp and the error went away.  I now get

(%i16) hgfred([-1/2,3/4],[7/4],-1);

SIMP2F1-WILL-CONTINUE-IN
(%o16) %f[2,1]([-1/2,3/4],[7/4],-1)

I don't always recompile everything from scratch, so there must be some bad
interaction between compiling parts of maxima and loading an old hyp.fasl.
What that could be, I don't know.  Perhaps some issue with special
variables.  (There are quite a few in hyp and hypgeo.)

Ray
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