Gillespie's Stochastic Simulation Algorithm (SSA) CRAN Task View: DifferentialEquations (http://CRAN.R-project.org/view=DifferentialEquations) GillespieSSA provides a simple to use, intuitive, and extensible interface to several stochastic simulation algorithms for generating simulated trajectories of finite population continuous-time model. Currently it implements Gillespie's exact stochastic simulation algorithm (Direct method) and several approximate methods (Explicit tau-leap, Binomial tau-leap, and Optimized tau-leap). The package also contains a library of template models that can be run as demo models and can easily be customized and extended. Currently the following models are included, decaying-dimerization reaction set, linear chain system, logistic growth model, Lotka predator-prey model, Rosenzweig-MacArthur predator-prey model, Kermack-McKendrick SIR model, and a metapopulation SIRS model. Software Depends: R (>= 2.0.0) Mario Pineda-Krch <mpineda@math.ualbeta.ca> Mario Pineda-Krch <mpineda@math.ualbeta.ca> GPL (>= 3) 2010-08-16 application/tgz http://CRAN.R-project.org/package=GillespieSSA