SciPy is a set of Open Source scientific and numeric tools for Python. It currently supports special functions, integration, ordinary differential equation (ODE) solvers, gradient optimization, genetic algorithms, parallel programming tools, an expression-to-C++ compiler for fast execution, and others.

Simply great. A comprehensive library for the development of scientific and technical tools in Python

SciPy is the greatest free alternative to MATLAB known to me, even superior in many aspects.