Eh? MATLAB's symbolic toolbox is just the textmode from Maple... which is pretty neat if you want to watch something do ascii drawings of various math symbols, lol.
And LAPACK has absolutely nothing to do with CAS. It's an open source numeric linear algebra package (in FORTRAN no less)--for general applications, it is the standard numeric linalg package. Most of MATLAB's linalg functions are just wrappers for LAPACK calls--i.e. MATLAB decides which LAPACK function is needed (is the matrix real? symmetric? banded? etc) and makes the appropriate call for you. Though, MATLAB doesn't support all of LAPACK's functionality.