DBETA

dbeta
The beta density function

         f = dbeta(x,a,b)
	Input	x	real
		a,b 	positive reals
		(x,a,b can be matrix with common dimensions)

	Output	f	beta density function with parameters a and b at the
			values of x :
			f=x.^(a-1) .* (1-x).^(b-1) ./ beta(a,b)1_{0<x<1}