2 1 - tanh (log(x)) ----------------- x
/ 2 \ (1 + 2*tanh(log(x)))*\-1 + tanh (log(x))/ ----------------------------------------- 2 x
/ 2 \ / 2 \ -2*\-1 + tanh (log(x))/*\3*tanh (log(x)) + 3*tanh(log(x))/ ---------------------------------------------------------- 3 x