Some software packages at Wikipedia here
At CASC (Center for Applied Scientific Computing) there is ODEPACK (Serial FORTRAN solvers for Ordinary Differential Equation initial value problems) here and BABEL:
"Babel provides high-performance language interoperability and middleware for scientific applications. It also provides coarse-grained distributed computing using remote method invocation. Babel currently supports C, C++, Java, Python, and various dialects of Fortran."
Also, you can try SUNDIALS (SUite of Nonlinear and DIfferential/ALgebraic equation Solvers) available here.
SUNDIALS provides a Matlab interface to CVODES (solves IVP for ODE systems), IDA (solves IVP dor DAE systems) and KINSOL (solves nonlinear algebraic problems).