#11590: Integrating the sgn() function can produce incorrect results
------------------------+---------------------------------------------------
Reporter: mjo | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone:
Component: calculus | Keywords:
Work_issues: | Upstream: Reported upstream. Developers
acknowledge bug.
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by mjo):
Something else is weird here. In standalone maxima-5.26, we don't get back
the wrong answer. But through sage, '''without''' abs_integrate, we get
`1/2`:
{{{
sage: integrate(x * sgn(x^2 - 1/4), x, -1, 0)
1/2
sage: maxima.console()
;;; Loading #P"/home/mjo/src/sage-5.0.beta1/local/lib/ecl/sb-bsd-
sockets.fas"
;;; Loading #P"/home/mjo/src/sage-5.0.beta1/local/lib/ecl/sockets.fas"
;;; Loading #P"/home/mjo/src/sage-5.0.beta1/local/lib/ecl/defsystem.fas"
;;; Loading #P"/home/mjo/src/sage-5.0.beta1/local/lib/ecl/cmp.fas"
Maxima 5.26.0 http://maxima.sourceforge.net
using Lisp ECL 11.1.1
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) 'integrate(x*signum(x^2-1/4),x);
(%o2) 'integrate(x*signum(x^2-1/4),x)
(%i3) 'integrate(x*signum(x^2-1/4),x,-1,0);
(%o3) 'integrate(x*signum(x^2-1/4),x,-1,0)
}}}
Intriguing!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11590#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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