docs: static public double griewank(double[] x) {
  
      double sum = 0.0;
      double product = 1.0;
  
      for (int i = 0; i < x.length; i++) {
        sum += ((x[i] * x[i]) / 4000.0);
        product *= Math.cos(x[i] / m_iSqrt[i]);
      }
  
      return (sum - product + 1.0);
    }