#12842: Incorrect sign in exponential integral via Maxima
-------------------------+--------------------------------------------------
Reporter: mjo | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: symbolics | Keywords:
Work issues: | Report Upstream: Not yet reported upstream; Will
do shortly.
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Reported by Laurent Decreusefond on sage-support:
{{{
sage: t = SR.symbol('t', domain='real')
sage: f = e^(-2*t)/sqrt(1-e^(-2*t))
sage: integrate(f,t,0,infinity)
-1
}}}
The sign is wrong, as the function is clearly positive. Just to check:
{{{
sage: numerical_integral(f, 0, infinity)
(0.99999999999919, 4.823208499260545e-09)
}}}
This is an upstream bug in Maxima:
{{{
Maxima 5.27.0 http://maxima.sourceforge.net
using Lisp ECL 12.2.1
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) display2d: false;
(%o1) false
(%i2) f: 1/(%e^(2*t)*sqrt(1-1/%e^(2*t)));
(%o2) %e^-(2*t)/sqrt(1-%e^-(2*t))
(%i3) integrate(f, t, 0, inf);
(%o3) -1
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12842>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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