x + x*atan(x)
x 1 + ------ + atan(x) 2 1 + x
/ 2 \ | x | 2*|1 - ------| | 2| \ 1 + x / -------------- 2 1 + x
/ 2 \ | x | 8*x*|-1 + ------| | 2| \ 1 + x / ----------------- 2 / 2\ \1 + x /