ppf method

double ppf(
  1. double q
)
override

Percent point function (inverse of cdf) at q of the given RV

Implementation

double ppf(double q) {
  double fac = math.ibetaInv(_halfDf, 0.5, 2 * math.min(q, 1 - q));
  double y = math.sqrt(df * (1 - fac) / fac);
  return (q > 0.5) ? y : -y;
}