Here is a script replicating some of the work presented on http://toxiclibs.org/2010/02/simutils-grayscott/ especially replicating this image http://toxiclibs.org/wp-content/uploads/2010/02/typeform_square_680....
Size of patterns depends on Grid size.
Time of calculation depends on grid size, _n_steps*jumps.
Image above was done using this script and bend, taper ... from Rhino, and also modifying feed and kill rates. See http://www.karlsims.com/rd.html