2 \cdot \tan^{-1} \left(\sqrt{\frac{1 - x}{1 + x}}\right)\tan^{-1} \left(\sqrt{\frac{1 - x}{1 + x}}\right) \cdot 2double f(double x) {
double r930568 = 2.0;
double r930569 = 1.0;
double r930570 = x;
double r930571 = r930569 - r930570;
double r930572 = r930569 + r930570;
double r930573 = r930571 / r930572;
double r930574 = sqrt(r930573);
double r930575 = atan(r930574);
double r930576 = r930568 * r930575;
return r930576;
}
double f(double x) {
double r930577 = 1.0;
double r930578 = x;
double r930579 = r930577 - r930578;
double r930580 = r930577 + r930578;
double r930581 = r930579 / r930580;
double r930582 = sqrt(r930581);
double r930583 = atan(r930582);
double r930584 = 2.0;
double r930585 = r930583 * r930584;
return r930585;
}



Bits error versus x
Results
Initial program 0.0
Final simplification0.0
herbie shell --seed 2019120
(FPCore (x)
:name "arccos"
(* 2 (atan (sqrt (/ (- 1 x) (+ 1 x))))))