Logarithm of beta function
L = betaln(Z,W)
L = betaln(Z,W) computes the natural logarithm of the beta function log(beta(Z,W)), for corresponding elements of arrays Z and W, without computing beta(Z,W). Since the beta function can range over very large or very small values, its logarithm is sometimes more useful.
Z and W must be real and nonnegative. They must be the same size, or either can be scalar.
x = 510 betaln(x,x) ans = -708.8616
-708.8616 is slightly less than log(realmin). Computing beta(x,x) directly would underflow (or be denormal).