/ 3 \ 2*pi*|2*x + -------| \ atan(x)/ -------------------- 2 / 2\ 3 \1 + x / *atan (x)
/ 2 \ | 4*x 6 9*x | -4*pi*|-1 + ------ + ----------------- + ----------------| | 2 / 2\ 2 / 2\ | \ 1 + x \1 + x /*atan (x) \1 + x /*atan(x)/ ---------------------------------------------------------- 2 / 2\ 3 \1 + x / *atan (x)