ibeta function

double ibeta(
  1. double a,
  2. double b,
  3. double x
)

The incomplete beta function. See: https://en.wikipedia.org/wiki/Beta_function#Incomplete_beta_function

Implementation

double ibeta(double a, double b, double x) {
  return ibetaReg(a, b, x) * beta(a, b);
}