Integration involving abs gives wrong result

[sagetrac-poeschko]

Running

sage: integrate(abs(sin(x)),(x,0,2*pi))

gives 0, but the correct result is 4.

This happens in version 4.6.1 . In 4.5.3, the integral was not evaluated at all.

Apply attachment: trac_10914.patch.

Upstream: Fixed upstream, in a later stable release.

Component: calculus

Author: Michael Orlitzky

Reviewer: Karl-Dieter Crisman

Merged: sage-5.0.beta14

Issue created by migration from https://trac.sagemath.org/ticket/10914

[kcrisman]

Upstream: Reported upstream. Little or no feedback.

[kcrisman]

comment:1

Certainly the integral better be positive!

This is wrong in Maxima (5.23.2), though it does get the one arch problem correct:

Maxima 5.23.2 http://maxima.sourceforge.net
using Lisp SBCL 1.0.24
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) integrate(abs(sin(x)),x,0,2*%pi);
(%o1)                                  0
(%i2) integrate(sin(x),x,0,%pi/2);
(%o2)                                  1
(%i3) 

This is now Maxima bug 3211915.

[kcrisman]

comment:2

Apparently that was a dup - see this bug report instead. Fixed, so when we upgrade we'll need a doctest.

[kcrisman]

Changed upstream from Reported upstream. Little or no feedback. to Fixed upstream, but not in a stable release.

[orlitzky]

comment:3

Well, we don't get 4, but at least the bug is fixed with our current Maxima.

[orlitzky]

Author: Michael Orlitzky

[orlitzky]

Changed upstream from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.

[kcrisman]

comment:4

shouln't?

Anyway, this is fine, but the style is a little too informal - those not having read the ticket will be mystified, and shouldn't have to go to the ticket to find out. So I'm uploading the same patch but with slightly different wording.

Notwithstanding that this file doesn't appear to be in the reference manual in any case.

[kcrisman]

Reviewer: Karl-Dieter Crisman

[kcrisman]

Attachment: trac_10914.patch.gz

Apply this patch only

[kcrisman]

comment:5

Apply attachment: trac_10914.patch.

[orlitzky]

comment:6

Ah, sorry. I actually parse it now as, "We won't get (an evaluated answer here, which is better than the previous (wrong) answer of zero)," but I don't think it matters much since most of them don't make sense out-of-context, "make sure #xyz is fixed."

[jdemeyer]

Merged: sage-5.0.beta14