#13869: Gamma of complex numbers incorrectly simplifies to factorial
----------------------------------------+-----------------------------------
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:
----------------------------------------+-----------------------------------
Comment (by JoalHeagney):
Hmm, maybe not. From what I can see from the maxima documentation, it's
kinda hinted that if you call makefact, it's assumed that you know what
you're asking for.
Would it be possible to change the simplification code to use makegamma
instead?
In the sage -maxima interface, I was able to do the following (these are
all out of order cut-and-paste from my maxima session.)
{{{
(%i18) makegamma(binomial(n,k)*factorial(k)*factorial(n-k));
(%o18) gamma(n + 1)
}}}
{{{
(%i12) gamma_expand:true;
(%o12) true
(%i13) gamma(2+i);
(%o13) i (i + 1) gamma(i)
(%i16) makegamma(binomial(n,k)*factorial(k)*factorial(n-k));
(%o16) n gamma(n)
}}}
The benefits here, are that makegamma and gamma_expand functions seem to
provide the same simplifications (if not more) that minfactorial and
makefact do, but gamma functions can handle (by definition) more fields
(RR, CC).
I don't know if we want gamma_expand to be true all the time, but it does
seem to give another level of simplification, pulling out i(i+1) in my
second example.
Then we could document the .makefact function so that users could convert
sagemath (new default) gamma answers to factorials for themselves?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13869#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
