Opened 9 years ago

Closed 8 years ago

#12842 closed defect (fixed)

Incorrect sign in exponential integral via Maxima

Reported by: mjo Owned by: burcin
Priority: major Milestone: sage-5.7
Component: symbolics Keywords:
Cc: kcrisman Merged in: sage-5.7.beta3
Authors: Punarbasu Purkayastha Reviewers: Michael Orlitzky
Report Upstream: Fixed upstream, in a later stable release. Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description

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

Attachments (1)

trac_12842-doctest.patch (679 bytes) - added by ppurka 8 years ago.
apply to devel/sage

Download all attachments as: .zip

Change History (16)

comment:1 Changed 9 years ago by mjo

  • Report Upstream changed from Not yet reported upstream; Will do shortly. to Reported upstream. Little or no feedback.

This is now Maxima bug 3517785.

comment:2 Changed 9 years ago by ppurka

  • Stopgaps set to todo

comment:3 Changed 9 years ago by kcrisman

  • Cc kcrisman added

comment:4 Changed 9 years ago by roed

  • Report Upstream changed from Reported upstream. Little or no feedback. to Reported upstream. No feedback yet.

comment:5 Changed 9 years ago by kcrisman

  • Report Upstream changed from Reported upstream. No feedback yet. to Fixed upstream, but not in a stable release.

Apparently fixed upstream. So it would probably end up in Maxima 5.28, due early August, if I recall correctly.

comment:6 Changed 9 years ago by kcrisman

Maxima 5.28 is now out. See #13364 to check whether it's in.

comment:7 Changed 8 years ago by ppurka

  • Status changed from new to needs_review

#13364 is in.

comment:8 Changed 8 years ago by ppurka

  • Report Upstream changed from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.
  • Status changed from needs_review to positive_review

comment:9 Changed 8 years ago by mjo

Is there a doctest for this bug in the maxima ticket? If not we should do one here.

Changed 8 years ago by ppurka

apply to devel/sage

comment:10 Changed 8 years ago by ppurka

  • Status changed from positive_review to needs_work

Added a doctest.

comment:11 Changed 8 years ago by ppurka

  • Status changed from needs_work to needs_review

comment:12 Changed 8 years ago by mjo

  • Reviewers set to mjo
  • Status changed from needs_review to positive_review

Maybe put the ticket number in the commit message, but the test looks good.

comment:13 Changed 8 years ago by jdemeyer

Please fill in the Author/Reviewer? fields with your real names.

comment:14 Changed 8 years ago by mjo

  • Authors set to Punarbasu Purkayastha
  • Reviewers changed from mjo to Michael Orlitzky
  • Stopgaps todo deleted

comment:15 Changed 8 years ago by jdemeyer

  • Merged in set to sage-5.7.beta3
  • Resolution set to fixed
  • Status changed from positive_review to closed
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