On Oct 1, 11:36 am, William Stein <wst...@gmail.com> wrote:
> On Thu, Oct 1, 2009 at 8:33 AM, Stan Schymanski <schym...@gmail.com> wrote:
>
> > I am really, really missing a function like MMA's Reduce in sage.
> > Typically, when I want to solve a complicated equation, sage throws
> > various questions generated by maxima at me, about whether variables
> > and certain terms are positive, zero, or negative. Some of them can be
> > answered a priori by appropriate assume() statements, others can't, so
> > I often run into a dead end and can't solve equations that would be
> > easily solved by MMA. Very frustrating.
>
> > Would it be hard to write a routine, which answers all of maxima's
> > questions with all possible answers and creates a new solution branch
> > for each answer? I think this is what MMA's Reduce does, and at the
> > end it presents the result as a list of nested conditions for each
> > solution. Would anyone else be interested in such a functionality and,
> > more importantly, would anyone have the know-how and time to implement
> > it?
>
> I think it would be very interesting to try to write such a function,
> and there are certainly people with the appropriate knowledge...
I've thought about this... one problem I've heard about this is that
it probably requires a program that answers Maxima questions on the
fly and tries again and again, keeping track of the results, which I'm
not sure if pexpect would easily support (?) ... can you interact
directly with Maxima that way?
A less urgent question would be what recursion depth would be
appropriate. Another is that this will definitely not always work,
since sometimes even assuming the things Maxima asks does not result
in the answer. This isn't necessarily a limitation of Maxima, since
some of these things probably don't have a finite decision routine -
but still annoying.
Still, this idea is worth trying for others to play with. Especially
if it were first implemented with a 1 or 2 level recursion, it would
help out with a lot of integrals and limits which just need to know
x>,<,==0. How efficient is Mma's Reduce for this sort of thing?
- kcrisman
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