*  @return cos(x) - 1
     */
    private static double polyCosine(double x) {
        double x2 = x*x;

        double p = 2.479773539153719E-5;
        p = p * x2 + -0.0013888888689039883;
        p = p * x2 + 0.041666666666621166;
        p = p * x2 + -0.49999999999999994;
        p *= x2;

        return p;
    }