ASCEND is an free open-source software program
EditBy: ASCEND is an free open-source software program for solving small to very large mathematical models. ASCEND can solve systems of non-Linear Equations, linear and nonlinear optimisation problems, and dynamic systems expressed in the form of differential/algebraic equations.

It offers:
* an object-oriented model description language for describing your system,
* an interactive user interface that allows you to solve your model and explore the effect of changing the model parameters, and
* a scripting environment that allows you to automate your more complex simulation problems.

A number of solvers are available including QRSlv (our nonlinear solver), CMSlv (a solver that includes provision for conditional modelling expressions, ie if Statements), LSODE (for ODE problems), IDA (for DAE problems), DOPRI5 (another ODE solver using Dormand-Prince method), CONOPT (a 3rd-party optimisation solver) and IPOPT (a FOSS optimization solver, still under development). you can free download ASCEND 0.9.7 now.