Math::Symbolic is intended to offer symbolic calculation capabilities to 
the Perl programmer without using external (and commercial) libraries 
and/or applications.

Possibly the most convenient way of constructing Math::Symbolic trees is 
using the builtin parser to generate trees from expressions such as '2 * 
x^5'. You may use the Math::Symbolic->parse_from_string() class method for 
this.

WWW: http://search.cpan.org/dist/Math-Symbolic/