A class library devoted to simulation, including an ODE solving package, as well as least square estimators, solvers, polynomials, basic statistics features. [Open source, BSD-like]
Connects Java and MATLAB. Native methods make it possible to use MATLAB's computational engine inside your own java applications, applets and servlets. [Freeware, source available]
Java classes for parsing and evaluating mathematical expressions. Supports multiple variables and user-defined functions. [Open source, GPL or commercial]