#11590: Integrating the sgn() function can produce incorrect results
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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 nbruin):
Replying to [comment:3 kcrisman]:
> Even with #11483, this isn't working right. It should, though - see
Barton's post at the Maxima ticket:
> {{{
> By the way:
>
> (%i4) load(abs_integrate)$
>
> Correct antiderivative:
>
> (%i5) 'integrate(x*signum(x^2-1/4),x);
> (%o5) abs(x^2-1/4)/2
>
> Correct definite integral
>
> (%i6) 'integrate(x*signum(x^2-1/4),x,-1,0);
> (%o6) -1/4
> }}}
> so I'm not sure why this is still returning the "wrong" thing.
Did you try it with `integrate` rather than `'integrate`? Given what we've
seen elsewhere in this ticket, I suspect it still gives the wrong answer.
In sage, we are interfacing with `integrate`. If that is still broken,
then the bug is not fixed as far as sage is concerned.
If maxima's position is that we should use a different integration routine
(i.e., `'integrate`) then we need a heuristic on when to use what routine
... isn't it maxima's job to figure this out?
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11590#comment:13>
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