#14821: Weird error in exponential integral
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Reporter: ppurka | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.12
Component: calculus | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by kcrisman):
Almost certainly the same error (see
[https://groups.google.com/forum/#!topic/sage-support/zpbCOeljVqI this
sage-support thread]:
{{{
sage: integral(exp(-300.0/(-0.064*x+14.0)),x,0.0,120.0)
}}}
and also [http://ask.sagemath.org/question/2028/def-fx-evaluvates-
individually-but-not-inside-plot this ask.sagemath question].
The real underlying issue is the one
[https://sourceforge.net/p/maxima/bugs/2510/ at this Maxima bug];
basically, we use `keepfloat:true` in Maxima so that things like the
integral of `e^(-x^2)` come out right, but this causes things to go wrong
in these examples.
And [https://groups.google.com/forum/#!topic/sage-devel/JZ54xk51F-E Nils'
comment] still applies, that it's not clear why something with a float in
it should be integrated symbolically (rather than numerically) at all. I
think this is an important point, though I'm not sure how to resolve it in
such a ridiculously simple case as yours. Note that I updated the Maxima
bug, and with `keepfloat:false` it is ridiculously accurate as a float.
That said, we should still have a better error message, and ideally just a
correct answer.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14821#comment:2>
Sage <http://www.sagemath.org>
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