pw.mac's pwint() has similar problems. I added some new test cases to
rtest_pw.mac. This is not easy to fix anymore, pw.mac has become complex.
Rich
-----Original Message-----
From: Barton Willis
Sent: Thursday, January 06, 2011 9:50 AM
To: Mark H Weaver
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] Bugs in abs_integrate.mac
Mark,
Thanks for the bug report and (especially) your clear and detailed analysis.
I have fixes for each of these bugs.
The fix for abs_defint(unit_step(x),x,99,100) is what you suggested.
To fix abs_defint(unit_step(unit_step(x)),x,-1,0), I changed the signum
representation for unit_step to
unit_step(x) = (signum(x)*(signum(x)+1))/2
Additionally, some abs_integrate functions convert terms such as
signum(nonconstant polynomial)^2 to 1. In the
context of an integrand signum(nonconstant polynomial)^2 = 1 is an OK
identity, I think.
It will take me some time to re-think and improve these fixes. Maybe you
could file a bug report--I like
having a record of bugs.
Again, thanks for your bug report.
--Barton
(author of abs_integrate)
-----maxima-bounces at math.utexas.edu wrote: -----
>I have found some bugs in abs_integrate.mac:
>(%i3) abs_defint(unit_step(x),x,99,100);
>(%o3) 100
>(%i4) abs_defint(unit_step(unit_step(x)),x,-1,0);
>(%o4) 1/2
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