DiffSim is no longer maintained. See https://launchpad.net/subcell instead.

DiffSim is a library for solving discrete and stochastic systems coupled with continuous and deterministic systems. DiffSim provides a simple declarative language for defining problems in Python. It has built in capabilities to solve the diffusion equation over an arbitrary numbers of domains. The domains can be coupled using boundary fluxes, and each domain can define several diffusive ligands.