The authors NSM and XPP code for the paper:

Ausborn J, Snyder AC, Shevtsova NA, Rybak IA, Rubin JE (2017) State-Dependent Rhythmogenesis and Frequency Control in a Half-Center Locomotor CPG. J Neurophysiol :10.1152/jn.00550.2017

is available at the web site:

http://neurobio.drexelmed.edu/rybakweb/software1.htm