>
> I've got a really *really* long expression in 16 variables, but I'm
> only interested in those parts of the expression that contain 4 of
> those 16 variables. Is there any way to get maxima to return the
> subexpression containing only those variables which I'm interested in?
>
An interesting problem. First step is to specify it more precisely. When
you say "4 of those 16 variables", I assume you mean a *specified* 4, not
any 4 (or more). Secondly, what do you mean by "the subexpression
containing [them]"?
For example, suppose you are "interested in" x and y, and the expression is
x*(y+a)
do you want x*(y+a)? or x*y?
If the expression is
(a+b)*sin(x)
do you want (a+b)*sin(x) or just sin(x)?
etc.
-s