dan.stanger@ieee.org writes:
> For cre expressions I could first check the head of the expression,
> to see if the variable list contains $X in the first place, if it does
> then I could look at the rest of the expression to see if it contains G28.
You should also take into account algebraic dependencies introduced by
the conversion from general form to CRE form.
(C1) rat(x+sqrt(x))-rat(x);
(D1)/R/ SQRT(x)
(C2) ?print(%)$
((MRAT SIMP (((MEXPT SIMP) |$x| ((RAT SIMP) 1 2)) |$x|)
(#:|SQRT(x)7891| #:|x7892|))
(#:|SQRT(x)7891| 1 1) . 1)
(C3)
Suppose you want to know if the expression in (D1) contains x. so you
look at the header and notice that |$x| corresponds to #:|x7892|, then
you check for the presence of #:|x7892| in the rest of the list and
you won't find it... except, of course, if $ALGEBRAIC is T, where you
could recursively apply your search to the TELLRAT properties of all
occurring `smaller' symbols.
Wolfgang
--
wjenkner@inode.at