On Jan 15, 2010, at 9:58 AM, Craig Citro wrote:
As to Craig's point, yes you can make another Maxima session, but in
general all internal Maxima use either uses _maxima_(), which calls
the "calculus" copy, or directly uses the "calculus" copy of Maxima.
For instance for assumptions we really want to only be using one
Maxima session.
Actually, that's not what I was saying. The point that I was making
(too briefly, apparently -- I was typing on my Droid :) ) is that we
already have two default sessions of maxima floating around: one in
sage.interfaces.maxima, which is what a call to maxima() from the
command line uses, and sage.calculus.calculus.maxima, which is what
gets used by the symbolics behind the scenes. So I have two questions:
1) Do we have two maxima sessions floating around on purpose? That is,
do we *want* the session we use for symbolic simplification to be a
different session than the one the user has access to from the command
line? (I could see an argument for doing this, but I'm not clear as to
whether it was on purpose or by accident.)
I think we do. Maxima sessions can have so much state that it's nice
to keep them separate to ensure consistency of the calculus modules.
Also, that means you won't be accidently clobbering your calculus
variables, functions, etc.
2) We start them with different options, which is why maxima("d2")
just returns d2, but sage.calculus.calculus.maxima("d2") returns the
factorial business that started this thread. Do we want to have some
of the options used to start sage.calculus.calculus.maxima also used
in sage.interfaces.maxima?
I also want to point out something that other people may have
realized, but has confused me before: if you're trying to do a
symbolic simplification, and maxima asks you a question, if you do
maxima("assume(x>0)") and try again, it will fail -- because it's
getting sent to the wrong maxima session:
sage: sqrt(x^2)
sqrt(x^2)
sage: sqrt(x^2).simplify()
sqrt(x^2)
sage: maxima.assume("x>0")
[x>0]
sage: sqrt(x^2).simplify()
sqrt(x^2)
sage: sage.calculus.calculus.maxima.assume("x>0")
[x>0]
sage: sqrt(x^2).simplify()
x
Do other people find this confusing?
Eventually (if not already) assumptions and the like will need to be
recorded and used at a higher level than the maxima interpreter
process, so I don't think we could always count on the above working.
- Robert
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