public static double p(double t, double s, int n, double r) { double num1 = FinMath.FV2(1.0, r, t / (double)n); double num2 = FinMath.u(t, s, n); double num3 = FinMath.d(t, s, n); return((num1 - num3) / (num2 - num3)); }