Hm. I misunderstood your question, thinking that the digits compose concrete numbers instead of symbols. Well, I think that BrowserUk has already provided a solution that probably suits your problem better than a generic Perl module for symbolic algebra. If you are still interested in such a module you could search CPAN for symbolic and/or algebra or perform a Super Search. This also sounds interesting: recommendations on scientific computing with Perl.

Maximum string size in Perl: AFIK, its only limited by your OS (e.g. 32bit/64bit) and your hardware (memory, disk). Experimentally, my Perl 5.8.4 on a 64bit Solaris 10 box (8GB) was able to create a string of at least 3945 MB (1MB = 1024 x 1024) before out-of-memory occurred.

Right, the equation got truncated. If you like, please surround your sample equation with <readmore>...</readmore> tags - although it won't fix the truncation effect, it will make this thread more readable.