#13869: Gamma of complex numbers incorrectly simplifies to factorial
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Reporter: JoalHeagney | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.6
Component: symbolics | Resolution:
Keywords: gamma, simplify_full | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Changes (by kcrisman):
* cc: benjaminfjones, dsm (added)
Comment:
In Sage 5.2:
{{{
sage: (gamma(-i-3/2)).simplify_full()
factorial(-I - 5/2)
sage: a = gamma(-i-3/2)
sage: a._maxima_().makefact()
(-%i-5/2)!
}}}
> This seems to be our doing. In `simplify_factorial()` we have:
So I agree with Burcin that this comes from us.
The problem is that we do rely on this for some examples of the (mostly
improved) simplification. E.g. from #6636
{{{
sage: var('k')
k
sage: f = binomial(n,k)*factorial(k)*factorial(n-k)
sage: f._maxima_()
k!*binomial(n,k)*(n-k)!
sage: f._maxima_().makefact()
n!
}}}
On the other hand, does Maxima really ''want'' these occurrences with non-
integer inputs to be transformed thusly?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13869#comment:2>
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