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