An R package accompanies our 2010 paper on fluctuation domains. The package includes the source code for simulations and R scripts that create each of the figures in the paper. This can be used to re-run simulations shown in the paper with different parameter values to explore how each influences the onset of fluctuations. Currently only tested on a Linux machine with GNU Standard Library (GSL) installed. The source code is now released on DRYAD using the Creative Commons public domain license.