code: private static double polySine(final double x)
      {
          double x2 = x*x;
  
          double p = 2.7553817452272217E-6;
          p = p * x2 + -1.9841269659586505E-4;
          p = p * x2 + 0.008333333333329196;
          p = p * x2 + -0.16666666666666666;
          //p *= x2;
          //p *= x;
          p = p * x2 * x;
  
          return p;
      }
docs: Computes sin(x) - x, where |x| < 1/16.
  Use a Remez polynomial approximation.
  @param x a number smaller than 1/16
  @return sin(x) - x