/ _______\ atan\\/ x - 1 /
atan(sqrt(x - 1))
1 ------------- _______ 2*x*\/ x - 1
/ 1 2\ -|------ + -| \-1 + x x/ -------------- ________ 4*x*\/ -1 + x
1 3 1 -- + ----------- + ------------ 2 2 2*x*(-1 + x) x 8*(-1 + x) ------------------------------- ________ x*\/ -1 + x