Malthus.R This is the equivalent R code for malthus.m provided on Jim Powell's website: http://www.math.usu.edu/powell/wauclass/labs.html This R code solves an integrodifference equation with 1 spatial dimension using the discrete fourier transform.
IDE_SI.R This is R code that solves a discretized version of an SIS model and assumes Gaussian dispersal for susceptible and infected hosts. The coupled IDEs are solved using discrete fast fourier transforms (ffts). I tried to write the code so that it would be easy to edit if you would like to simulate a different type of population dynamic.