R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1}{2}\right) \cdot \cos \left(\frac{\phi_2}{2}\right) - \cos \left(\frac{\phi_1}{2}\right) \cdot \sin \left(\frac{\phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1}{2}\right) \cdot \cos \left(\frac{\phi_2}{2}\right) - \cos \left(\frac{\phi_1}{2}\right) \cdot \sin \left(\frac{\phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \left(\sin \left(\frac{\lambda_1}{2}\right) \cdot \cos \left(\frac{\lambda_2}{2}\right) - \cos \left(\frac{\lambda_1}{2}\right) \cdot \sin \left(\frac{\lambda_2}{2}\right)\right)\right) \cdot \left(\sin \left(\frac{\lambda_1}{2}\right) \cdot \cos \left(\frac{\lambda_2}{2}\right) - \cos \left(\frac{\lambda_1}{2}\right) \cdot \sin \left(\frac{\lambda_2}{2}\right)\right)\right)}}\right)double code(double R, double lambda1, double lambda2, double phi1, double phi2) {
return ((double) (R * ((double) (2.0 * ((double) atan2(((double) sqrt(((double) (((double) pow(((double) sin(((double) (((double) (phi1 - phi2)) / 2.0)))), 2.0)) + ((double) (((double) (((double) (((double) cos(phi1)) * ((double) cos(phi2)))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0)))))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0)))))))))), ((double) sqrt(((double) (1.0 - ((double) (((double) pow(((double) sin(((double) (((double) (phi1 - phi2)) / 2.0)))), 2.0)) + ((double) (((double) (((double) (((double) cos(phi1)) * ((double) cos(phi2)))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0)))))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0))))))))))))))))));
}
double code(double R, double lambda1, double lambda2, double phi1, double phi2) {
return ((double) (R * ((double) (2.0 * ((double) atan2(((double) sqrt(((double) (((double) pow(((double) (((double) (((double) sin(((double) (phi1 / 2.0)))) * ((double) cos(((double) (phi2 / 2.0)))))) - ((double) (((double) cos(((double) (phi1 / 2.0)))) * ((double) sin(((double) (phi2 / 2.0)))))))), 2.0)) + ((double) (((double) (((double) (((double) cos(phi1)) * ((double) cos(phi2)))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0)))))) * ((double) sin(((double) (((double) (lambda1 - lambda2)) / 2.0)))))))))), ((double) sqrt(((double) (1.0 - ((double) (((double) pow(((double) (((double) (((double) sin(((double) (phi1 / 2.0)))) * ((double) cos(((double) (phi2 / 2.0)))))) - ((double) (((double) cos(((double) (phi1 / 2.0)))) * ((double) sin(((double) (phi2 / 2.0)))))))), 2.0)) + ((double) (((double) (((double) (((double) cos(phi1)) * ((double) cos(phi2)))) * ((double) (((double) (((double) sin(((double) (lambda1 / 2.0)))) * ((double) cos(((double) (lambda2 / 2.0)))))) - ((double) (((double) cos(((double) (lambda1 / 2.0)))) * ((double) sin(((double) (lambda2 / 2.0)))))))))) * ((double) (((double) (((double) sin(((double) (lambda1 / 2.0)))) * ((double) cos(((double) (lambda2 / 2.0)))))) - ((double) (((double) cos(((double) (lambda1 / 2.0)))) * ((double) sin(((double) (lambda2 / 2.0))))))))))))))))))))));
}



Bits error versus R



Bits error versus lambda1



Bits error versus lambda2



Bits error versus phi1



Bits error versus phi2
Results
Initial program 23.8
rmApplied div-sub23.8
Applied sin-diff24.0
rmApplied div-sub24.0
Applied sin-diff23.5
rmApplied div-sub23.5
Applied sin-diff22.9
rmApplied div-sub22.9
Applied sin-diff13.4
Final simplification13.4
herbie shell --seed 2020128
(FPCore (R lambda1 lambda2 phi1 phi2)
:name "Distance on a great circle"
:precision binary64
(* R (* 2.0 (atan2 (sqrt (+ (pow (sin (/ (- phi1 phi2) 2.0)) 2.0) (* (* (* (cos phi1) (cos phi2)) (sin (/ (- lambda1 lambda2) 2.0))) (sin (/ (- lambda1 lambda2) 2.0))))) (sqrt (- 1.0 (+ (pow (sin (/ (- phi1 phi2) 2.0)) 2.0) (* (* (* (cos phi1) (cos phi2)) (sin (/ (- lambda1 lambda2) 2.0))) (sin (/ (- lambda1 lambda2) 2.0))))))))))