Implement the HilleRisLambers et al. 2001 model for arid vegetation in Julia

padcirc.jl and perlap.jl are the functions I wrote to calculate the diffusion operator with periodic boundary conditions.

hillerislambers.jl is a script which runs the model.
HilleRisLambers.dat is the output suitable for gnuplot.
julia.png is the plot derived from gnuplot.