Download of maxima-5.45.1s-win32.exe (maxima-5.45.1s-win32.exe ( external link: SF.net): 140,032,640 bytes) will begin shortly. If not so, click link on the left.
Maxima is a fairly complete computer algebra system written in Common Lisp with an emphasis on symbolic computation. It is based on DOE-MACSYMA and licensed under the GPL. Its abilities include symbolic integration, 3D plotting, and an ODE solver.