docs: public static double quantile(double val, double sigma) {
      if(!(val >= 0.) || !(val <= 1.)) {
        return Double.NaN;
      }
      if(val == 0.) {
        return 0.;
      }
      if(val == 1.) {
        return Double.POSITIVE_INFINITY;
      }
      return sigma * FastMath.sqrt(-2. * FastMath.log(1. - val));
    }