Matlab (for Matrix Laboratory) is a programming language, e.g., you can compile the source code into .exe file. It is superior in matrix operation, computation, simulation to SAS. it is easier to customize to suit your need.
SAS, on the other hand, is a script language, e.g., you can't compile code into .exe file. It is very hard to debug, and extremely hard to customize. It can handle very large dataset.