Robert Dodier <robert.dodier at gmail.com> wrote: On 23 Jan 2007 17:23:55 +0100, Albert Reiner wrote:
> [Ray Tice , Mon, 22 Jan 2007 14:38:25 -0800 (PST)]:
> > How do I reformulate functions that use abs or max so that maxima
> > can integrate them? For example, integrate(abs(x), x, -1, 1) won't
> > evaluate, but both of these will:
> > integrate(abs(x), x, -1, 0)
> > integrate(abs(x), x, 0, 1)
>
> I believe, the correct way to handle these kinds of things is to
> replace abs(x) by something akin to (if x >= 0 then x else -x).
> Someone has done some work on unevaluated conditionals that should
> allow you to do this.
The boolsimp package makes Maxima comfortable with unevaluated
conditionals, but there aren't any functions to make conditionals
interact with integrate or arithmetic operators. Not for any principled
reason, but just because I haven't gotten around to it.
This is an interesting problem; I'll try to work on it over the weekend.
best,
Robert Dodier
Thanks for the suggestion Albert. It didn't quite work out on Maxima 5.11.0:
"Maxima was unable to evaluate the predicate:x>=0"
Robert, glad I got you enthused.
Thanks both!
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