#18210: Symbolic computation of Gamma related function crashes Sage
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Reporter: VivianePons | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.7
Component: symbolics | Resolution:
Keywords: sd67 | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by buck):
@rws: This is a reposting of my sage-support thread
[https://groups.google.com/forum/#!topic/sage-support/E2YW4ddcwQI here]
where I gave some small reproductions of the problem.
----
The incomplete gamma function is resulting in negative outputs with
positive real input, which shouldn't happen.
{{{
sage: gamma(60, 30).numerical_approx()
-1.28306738270893e74
}}}
Attached is a notebook showing the same in graphical form.
If I feed in numbers of a higher precision, I get the correct result:
{{{
sage: R10 = RealField(200)
sage: gamma(R10(60), R10(30)).numerical_approx()
1.38682990237888e80
}}}
My final problem is that there doesn't seem to be any way to get higher
precision numbers to feed all the way through the plot function:
{{{
sage: show(plot3d(log(gamma(k, k*x)), (x, R10(0), R10(5/2)), (k, R10(1),
R10(101))))
Launched jmol viewer for Graphics3d Object
}}}
(you would see a 3d graph with a bite out of it where the precision issue
exists)
----
I'm able to reproduce it today on the latest sage:
{{{
$ ./sage -v
SageMath Version 6.7.beta1, Release Date: 2015-04-15
$ ./sage
sage: gamma(60, 30).numerical_approx()
-1.28306738270893e74
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/18210#comment:13>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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