sin(atan(5*x))
5 -------------- 3/2 / 2\ \1 + 25*x /
-375*x -------------- 5/2 / 2\ \1 + 25*x /
/ 2 \ | 125*x | 375*|-1 + ---------| | 2| \ 1 + 25*x / -------------------- 5/2 / 2\ \1 + 25*x /