\frac{r \cdot \sin b}{\cos \left(a + b\right)}r \cdot \left(\sin b \cdot \frac{1}{\cos b \cdot \cos a - \sin a \cdot \sin b}\right)double code(double r, double a, double b) {
return ((r * sin(b)) / cos((a + b)));
}
double code(double r, double a, double b) {
return (r * (sin(b) * (1.0 / ((cos(b) * cos(a)) - (sin(a) * sin(b))))));
}



Bits error versus r



Bits error versus a



Bits error versus b
Results
Initial program 14.9
rmApplied cos-sum0.3
rmApplied *-un-lft-identity0.3
Applied times-frac0.3
Simplified0.3
Simplified0.3
rmApplied div-inv0.4
Final simplification0.4
herbie shell --seed 2020057 +o rules:numerics
(FPCore (r a b)
:name "r*sin(b)/cos(a+b), A"
:precision binary64
(/ (* r (sin b)) (cos (+ a b))))