#11483: enable abs_integrate package from maxima
-------------------------------------------------+--------------------------
Reporter: kcrisman | Owner: burcin
Type: enhancement | Status: closed
Priority: major | Milestone: sage-5.0
Component: calculus | Resolution: fixed
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: Karl-Dieter
Crisman
Authors: Michael Orlitzky, Jason Grout | Merged in:
sage-5.0.beta3
Dependencies: #12094 | Stopgaps:
-------------------------------------------------+--------------------------
Comment (by dimpase):
abs_integrate can't do easy things like integrate(abs(cos(x)),x) right.
{{{
(%i8) integrate(abs(cos(x)),x);
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
log: encountered log(0).
(%o8) 2*((1/2-sin(x)/((cos(x)+1)*(sin(x)^2/(cos(x)+1)^2+1)))
*signum(sin(x)/(cos(x)+1)-1)
+1)*signum(sin(x)/(cos(x)+1)+1)
}}}
and the resulting expression is wrong, as it is 1 at 0, and not 0. As a
result, we get {{{integrate(abs(cos(x)),x,0,pi)==-1}}}.
Needless to say, same happens in Sage:
{{{
sage: integrate(abs(cos(x)),(x,0,pi))
-1
}}}
This is with maxima 5.26, as well as with 5.29, see #13364.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11483#comment:12>
Sage <http://www.sagemath.org>
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