It very much depends on * what * exactly you want to do. I have done some number crunching in Perl (processing many GB's of data) and it worked fine for me. You would expect C to have better performance though.

Some matrix operations can be notoriously tricky, especially if the matrices get big and/or the numbers have high precision. A lot of stuff was developed in mathematics to tackle this.

So you typically want to use some C-library or Perl module tailored for this. You can take a look at Math::Matrix (Perl) or try your luck with some C math library. Check for example http://www.ibm.com/developerworks/opensource/library/l-matrix.html