\frac{r \cdot \sin b}{\cos \left(a + b\right)}r \cdot \frac{\sin b}{\cos b \cdot \cos a - \sin a \cdot \sin b}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) / ((cos(b) * cos(a)) - (sin(a) * sin(b)))));
}



Bits error versus r



Bits error versus a



Bits error versus b
Results
Initial program 15.0
rmApplied cos-sum0.3
rmApplied *-un-lft-identity0.3
Applied times-frac0.3
Simplified0.3
Simplified0.3
Final simplification0.3
herbie shell --seed 2020092
(FPCore (r a b)
:name "r*sin(b)/cos(a+b), A"
:precision binary64
(/ (* r (sin b)) (cos (+ a b))))