R/betaABfromMeanKappa.R

In ndbrown6/lazypuppy: Doing Bayesian Data Analysis 2nd Edition

'betaABfromMeanKappa' <- function(mean,
								  kappa)
{
	if (mean<=0 | mean>=1) {
		stop("must have 0 < mean < 1")
	}
	if (kappa<=0) {
		stop("kappa must be > 0")
	}
	a = mean*kappa
	b = (1.0-mean)*kappa
	return(invisible(list(a=a, b=b)))
}