"SciPy (pronounced "Sigh Pie") is open-source software for mathematics, science, and engineering. It is also the name of a very popular conference on scientific programming with Python."
"The open source tools that I explore in this article are (with their associated licenses):: Gnuplot (GPL); GNU Octave (GPL); Scilab (Scilab); MayaVi (BSD); Maxima (GPL)"