XPPAUT

XPPAUT is a tool for solving

* differential equations,

* difference equations,

* delay equations,

* functional equations,

* boundary value problems, and

* stochastic equations.

The code brings together a number of useful algorithms and is extremely portable. All the graphics and interface are written completely in Xlib which explains the somewhat idiosyncratic and primitive widgets interface.

Homepage: http://www.math.pitt.edu/~bard/xpp/xpp.html