Hi and thanks both for your replies. xreplace doesn't look like something I'd be interested in using, but as a very superficial approximation, it looks like replace changes the expression lexicographically but subs changes the expression mathematically. I know I know that's *very* superficial but I'll be back if I have any further problems later. The following error message which I got was very useful to know as well:
>>> e=x**2 >>> e.replace(2,3) TypeError: first argument to replace() must be a type, an expression or a callable -- Shriramana Sharma -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
