StatsBetaCDF
StatsBetaCDF (x, p, q [, a, b])
The StatsBetaCDF function returns the beta cumulative distribution function
where B(p,q) is the beta function
The defaults (a =0 and b =1) correspond to the standard beta distribution were a is the location parameter, (b -a ) is the scale parameter, and p and q are shape parameters.
References
Evans, M., N. Hastings, and B. Peacock, Statistical Distributions, 3rd ed., Wiley, New York, 2000.