atan(x) e
d / atan(x)\ --\e / dx
atan(x) e -------- 2 1 + x
atan(x) (1 - 2*x)*e ------------------ 2 / 2\ \1 + x /
/ 2 \ | 1 6*x 8*x | atan(x) |-2 + ------ - ------ + ------|*e | 2 2 2| \ 1 + x 1 + x 1 + x / ---------------------------------------- 2 / 2\ \1 + x /