/ 2 \ acot\x - 1/
acot(x^2 - 1)
-2*x ------------- 2 / 2 \ 1 + \x - 1/
/ 2 / 2\\ | 4*x *\-1 + x /| 2*|-1 + --------------| | 2| | / 2\ | \ 1 + \-1 + x / / ----------------------- 2 / 2\ 1 + \-1 + x /
/ 2\ | 2 / 2\ | | 2 8*x *\-1 + x / | 8*x*|-3 + 5*x - ---------------| | 2| | / 2\ | \ 1 + \-1 + x / / --------------------------------- 2 / 2\ | / 2\ | \1 + \-1 + x / /