always simplify hypergeometric() when it's a polynomial

[rwst]

See https://groups.google.com/forum/?hl=en#!topic/sage-devel/8z2HyH5Y8Dc with Fredrik's assessment:

"For Sage, fixing the problem is actually trivial: when the hypergeometric function is a polynomial (and at least when the inputs are exact), don't call mpmath; just evaluate the polynomial directly and then call .n() on the result."

Component: symbolics

Keywords: special, functions, pFq, evaluation

Author: Ralf Stephan

Branch/Commit: u/rws/work_around_mpmath_problem_with_hypergeometric___zeroes @ 0e0fef6

Issue created by migration from https://trac.sagemath.org/ticket/17066

[rwst]

Branch: u/rws/work_around_mpmath_problem_with_hypergeometric___zeroes

[rwst]

Commit: b6f0fbc

[rwst]

comment:2

This patch just changes hypergeometric() to always invoke Maxima_lib.hgfred().

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New commits:

b6f0fbc

17066: always try to simplify

[rwst]

Author: Ralf Stephan

[kcrisman]

comment:3

Maybe document the problem at ask.sagemath is fixed, too?

hypergeometric([-2,-1],[2],-1).n(100)

was the example Dima posted on sage-devel...

[rwst]

comment:4

The "solution" is tongue-in-cheek, anyway, at least its application should be restricted in order to not burn CPU needlessly with higher orders of the function.

[kcrisman]

comment:5

Perhaps, but it wouldn't be hard to restrict it properly, right?