Another find of the FEM study is Octave, a great Math package.
Octave is a reimplementation of part of Matlab developed by Professor John Eaton at the University of Texas, Austin, and later at the University of Wisconsin, Madison.
If you are looking for an Open source alternative to Matlab you should give Octave a try.
William Stein’s article from 2007 on how Octave relates to Sage.
Sine 3D example, taken from the network-theory.co.uk GNU Octave Manual, code:
tx = ty = linspace (-8, 8, 41)';
[xx, yy] = meshgrid (tx, ty);
r = sqrt (xx .^ 2 + yy .^ 2) + eps;
tz = sin (r) ./ r;
mesh (tx, ty, tz);