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 r185530 = 2.0;
double r185531 = 1.0;
double r185532 = x;
double r185533 = r185531 - r185532;
double r185534 = r185531 + r185532;
double r185535 = r185533 / r185534;
double r185536 = sqrt(r185535);
double r185537 = atan(r185536);
double r185538 = r185530 * r185537;
return r185538;
}
double f(double x) {
double r185539 = 1.0;
double r185540 = x;
double r185541 = r185539 - r185540;
double r185542 = r185539 + r185540;
double r185543 = r185541 / r185542;
double r185544 = sqrt(r185543);
double r185545 = atan(r185544);
double r185546 = 2.0;
double r185547 = r185545 * r185546;
return r185547;
}



Bits error versus x
Results
Initial program 0.0
Final simplification0.0
herbie shell --seed 2019152
(FPCore (x)
:name "arccos"
(* 2 (atan (sqrt (/ (- 1 x) (+ 1 x))))))