We mainly use R for numerical implementations, code can be found here. You can install R on your computer via CRAN. Load the code into R and run the function with the appropriate parameters fixed. Usually default values of parameters are provided.
Numerical and MC-integration of a 1d integral
Simulation of numbers of long runs for random walks and their statistics
Simulation and (beautiful) visualization of stochastic 3d-population dynamics according to a Wishart process