/ 3\ | 1 - 2*x | 6*|2 + --------| | 3 | \ x / ---------------- x
/ 3\ 6*\1 - 2*x / 12 + ------------ 3 x ----------------- x
3 6 - 12*x 12 + --------- 3 x -------------- x
6.0*(2.0 + (1.0 - 2.0*x^3)/x^3)/x
/ 3\ 6*\1 - 2*x / 12 + ------------ 3 x ----------------- x