Freemat is an interpreted, matrix-oriented development environment for engineering and scientific applications, similar to the commercial package MATLAB. Freemat provides visualization, image manipulation, and plotting as well as parallel programming.
A dynamic and object-oriented programming language for developing extensions of modifiable applications. Features: OOP, flexible syntax, vectorial operations, dynamic linked lists, IDE, HTML generator, includeable DLL an so on.
Franklin Math is an open source Java symbolic computer algebra system (CAS), with similarities to commercial math packages such as MATLAB or Mathematica. It allows numeric and symbolic calculations, with built-in functions including plotting commands.