Syntax:
BETA(a:number, b:number)
Returns the value of the Beta function for parameters a and b.
One definition of the Beta function is
Β(a, b) = Γ(a) · Γ(b) ÷ Γ(a + b)
This special function is actually evaluated by Fireworkz using the formula
Β(a, b) = exp( gammaln(a) + gammaln(b) - gammaln(a + b) )