\cos^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{v \cdot v - 1}\right)\cos^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{\left(-1 \cdot 1\right) + {v}^{4}} \cdot \left(v \cdot v + 1\right)\right)double code(double v) {
return acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
double code(double v) {
return acos((((1.0 - (5.0 * (v * v))) / (-(1.0 * 1.0) + pow(v, 4.0))) * ((v * v) + 1.0)));
}



Bits error versus v
Results
Initial program 0.6
rmApplied flip--0.6
Applied associate-/r/0.6
Simplified0.6
Final simplification0.6
herbie shell --seed 2020078
(FPCore (v)
:name "Falkner and Boettcher, Appendix B, 1"
:precision binary64
(acos (/ (- 1 (* 5 (* v v))) (- (* v v) 1))))