\cos^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{v \cdot v - 1}\right)\frac{\pi}{2} - \sin^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{{\left(v \cdot v\right)}^{3} - {1}^{3}} \cdot \left(\left(v \cdot v\right) \cdot \left(v \cdot v\right) + \left(1 \cdot 1 + \left(v \cdot v\right) \cdot 1\right)\right)\right)double code(double v) {
return acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
double code(double v) {
return ((((double) M_PI) / 2.0) - asin((((1.0 - (5.0 * (v * v))) / (pow((v * v), 3.0) - pow(1.0, 3.0))) * (((v * v) * (v * v)) + ((1.0 * 1.0) + ((v * v) * 1.0))))));
}



Bits error versus v
Results
Initial program 0.6
rmApplied acos-asin0.6
rmApplied flip3--0.6
Applied associate-/r/0.6
Final simplification0.6
herbie shell --seed 2020053
(FPCore (v)
:name "Falkner and Boettcher, Appendix B, 1"
:precision binary64
(acos (/ (- 1 (* 5 (* v v))) (- (* v v) 1))))