id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
11590 Integrating the sgn() function can produce incorrect results mjo burcin "Actual result:
{{{
sage: integrate(x * sgn(x^2 - 1/4), x, -1, 0)
1/2
}}}
Since the argument to sgn() has only one root, -1/2, on (-1, 0), there are only two subintervals on which sgn() can have different values. In particular,
{{{
sage: sgn(x^2 - 1/4)(x = -0.75)
1
sage: sgn(x^2 - 1/4)(x = -0.25)
-1
}}}
Now, the original, actual result should be equivalent to the sum of the following:
{{{
sage: integrate(x, x, -1, -0.5)
-0.375
sage: integrate(-x, x, -0.5, 0)
0.125
}}}
So, something went wrong during the initial integration." defect new major calculus nbruin Fixed upstream, in a later stable release. #12731