public double Quantile(Probability p)
{
double x = BetaFunction.RegularizedIncompleteInverseValue(0.5 * df, 0.5, 2 * Min(p, 1 - p));
x = Sqrt(df * (1 - x) / x);
return(p >= 0.5 ? x : -x);
}
public double Quantile(Probability p) => BetaFunction.RegularizedIncompleteInverseValue(Alpha, Beta, p);