\tan^{-1} \left(\frac{\sqrt{{\left(\cos a \cdot \cos b\right)}^{2} + {\left(\cos a \cdot \sin b\right)}^{2}}}{\sin a}\right)\tan^{-1} \left(\frac{\sqrt{{\left(\cos a \cdot \cos b\right)}^{2} + {\left(\cos a \cdot \sin b\right)}^{2}}}{\sin a}\right)double code(double a, double b) {
return ((double) atan(((double) (((double) sqrt(((double) (((double) pow(((double) (((double) cos(a)) * ((double) cos(b)))), 2.0)) + ((double) pow(((double) (((double) cos(a)) * ((double) sin(b)))), 2.0)))))) / ((double) sin(a))))));
}
double code(double a, double b) {
return ((double) atan(((double) (((double) sqrt(((double) (((double) pow(((double) (((double) cos(a)) * ((double) cos(b)))), 2.0)) + ((double) pow(((double) (((double) cos(a)) * ((double) sin(b)))), 2.0)))))) / ((double) sin(a))))));
}



Bits error versus a



Bits error versus b
Results
Initial program 0.1
Final simplification0.1
herbie shell --seed 2020153
(FPCore (a b)
:name "(atan (/ (sqrt (+ (pow (* (cos a) (cos b)) 2) (pow (* (cos a) (sin b)) 2))) (sin a)))"
:precision binary64
(atan (/ (sqrt (+ (pow (* (cos a) (cos b)) 2.0) (pow (* (cos a) (sin b)) 2.0))) (sin a))))