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



Bits error versus r



Bits error versus a



Bits error versus b
Results
Initial program 15.2
rmApplied cos-sum0.3
rmApplied expm1-log1p-u0.3
rmApplied *-un-lft-identity0.3
Applied *-commutative0.3
Applied times-frac0.4
Simplified0.4
Simplified0.4
Final simplification0.4
herbie shell --seed 2020114 +o rules:numerics
(FPCore (r a b)
:name "r*sin(b)/cos(a+b), A"
:precision binary64
(/ (* r (sin b)) (cos (+ a b))))