#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 kcrisman):
> Did you try it with `integrate` rather than `'integrate`?
{{{
(%i5) display2d:false;
(%o5) false
(%i6) integrate(x*signum(x^2-1/4),x,-1,0);
(%o6) 1/2
(%i7) 'integrate(x*signum(x^2-1/4),x,-1,0);
(%o7) -1/4
}}}
Note that this was just Barton Willis (Maxima dev) example.
> 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.
I don't think they claimed it was fixed.
> 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?
Yes, I am a little stumped on this. I thought that the apostrophe just
meant "don't evaluate nounform", but apparently I was mistaken. I just
reported this example on the Maxima ticket, but I wouldn't hold my breath
waiting for it, since there ''is'' a way to get it to work correctly
there.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11590#comment:14>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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