The calculations are based on the model in Andersen and Brander PNAS 106(28) 11657-11660 (2009). Note that the model is based on a number of assumptions, see the article for details. Output of the model should not be used in a practical management setting without first consulting the authors. The R code for the model is here.
Php code by Casper Berg. R-code by Ken Andersen. September 2009.