atan(x) ------- x
1 atan(x) ---------- - ------- / 2\ 2 x*\1 + x / x
/ 1 atan(x) 1 \ 2*|- --------- + ------- - -----------| | 2 3 2 / 2\| | / 2\ x x *\1 + x /| \ \1 + x / /
/ 3*atan(x) 2 3 4*x \ 2*|- --------- + ----------- + ----------- + ---------| | 4 2 3 / 2\ 3| | x / 2\ x *\1 + x / / 2\ | \ x*\1 + x / \1 + x / /