Average Error: 0.9 → 0.2
Time: 1.1min
Precision: binary64
\[\lambda_1 + \tan^{-1}_* \frac{\cos \phi_2 \cdot \sin \left(\lambda_1 - \lambda_2\right)}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]
↓
\[\lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)}{\left(\cos \phi_1 + \cos \lambda_2 \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)\right) + \cos \phi_2 \cdot \log \left(e^{\sin \lambda_1 \cdot \sin \lambda_2}\right)}\]
\lambda_1 + \tan^{-1}_* \frac{\cos \phi_2 \cdot \sin \left(\lambda_1 - \lambda_2\right)}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}
↓
\lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)}{\left(\cos \phi_1 + \cos \lambda_2 \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)\right) + \cos \phi_2 \cdot \log \left(e^{\sin \lambda_1 \cdot \sin \lambda_2}\right)}
(FPCore (lambda1 lambda2 phi1 phi2)
 :precision binary64
 (+
  lambda1
  (atan2
   (* (cos phi2) (sin (- lambda1 lambda2)))
   (+ (cos phi1) (* (cos phi2) (cos (- lambda1 lambda2)))))))
↓
(FPCore (lambda1 lambda2 phi1 phi2)
 :precision binary64
 (+
  lambda1
  (atan2
   (+
    (* (cos lambda2) (* (sin lambda1) (cos phi2)))
    (* (sin (- lambda2)) (* (cos phi2) (cos lambda1))))
   (+
    (+ (cos phi1) (* (cos lambda2) (* (cos phi2) (cos lambda1))))
    (* (cos phi2) (log (exp (* (sin lambda1) (sin lambda2)))))))))
double code(double lambda1, double lambda2, double phi1, double phi2) {
	return lambda1 + atan2((cos(phi2) * sin(lambda1 - lambda2)), (cos(phi1) + (cos(phi2) * cos(lambda1 - lambda2))));
}
↓
double code(double lambda1, double lambda2, double phi1, double phi2) {
	return lambda1 + atan2(((cos(lambda2) * (sin(lambda1) * cos(phi2))) + (sin(-lambda2) * (cos(phi2) * cos(lambda1)))), ((cos(phi1) + (cos(lambda2) * (cos(phi2) * cos(lambda1)))) + (cos(phi2) * log(exp(sin(lambda1) * sin(lambda2))))));
}

Error

Bits error versus lambda1

Bits error versus lambda2

Bits error versus phi1

Bits error versus phi2

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Initial program 0.9

    \[\lambda_1 + \tan^{-1}_* \frac{\cos \phi_2 \cdot \sin \left(\lambda_1 - \lambda_2\right)}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]
  2. Using strategy rm

  3. Applied sub-neg_binary64_10940.9

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \phi_2 \cdot \sin \color{blue}{\left(\lambda_1 + \left(-\lambda_2\right)\right)}}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]

  4. Applied sin-sum_binary64_12340.8

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \phi_2 \cdot \color{blue}{\left(\sin \lambda_1 \cdot \cos \left(-\lambda_2\right) + \cos \lambda_1 \cdot \sin \left(-\lambda_2\right)\right)}}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]

  5. Applied distribute-rgt-in_binary64_10510.8

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\color{blue}{\left(\sin \lambda_1 \cdot \cos \left(-\lambda_2\right)\right) \cdot \cos \phi_2 + \left(\cos \lambda_1 \cdot \sin \left(-\lambda_2\right)\right) \cdot \cos \phi_2}}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]

  6. Simplified0.8

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\color{blue}{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right)} + \left(\cos \lambda_1 \cdot \sin \left(-\lambda_2\right)\right) \cdot \cos \phi_2}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]

  7. Simplified0.8

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \color{blue}{\sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}}{\cos \phi_1 + \cos \phi_2 \cdot \cos \left(\lambda_1 - \lambda_2\right)}\]
  8. Using strategy rm

  9. Applied cos-diff_binary64_12380.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}{\cos \phi_1 + \cos \phi_2 \cdot \color{blue}{\left(\cos \lambda_1 \cdot \cos \lambda_2 + \sin \lambda_1 \cdot \sin \lambda_2\right)}}\]

  10. Applied distribute-rgt-in_binary64_10510.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}{\cos \phi_1 + \color{blue}{\left(\left(\cos \lambda_1 \cdot \cos \lambda_2\right) \cdot \cos \phi_2 + \left(\sin \lambda_1 \cdot \sin \lambda_2\right) \cdot \cos \phi_2\right)}}\]

  11. Applied associate-+r+_binary64_10330.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}{\color{blue}{\left(\cos \phi_1 + \left(\cos \lambda_1 \cdot \cos \lambda_2\right) \cdot \cos \phi_2\right) + \left(\sin \lambda_1 \cdot \sin \lambda_2\right) \cdot \cos \phi_2}}\]

  12. Simplified0.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}{\color{blue}{\left(\cos \phi_1 + \cos \lambda_2 \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)\right)} + \left(\sin \lambda_1 \cdot \sin \lambda_2\right) \cdot \cos \phi_2}\]
  13. Using strategy rm

  14. Applied add-log-exp_binary64_11400.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)}{\left(\cos \phi_1 + \cos \lambda_2 \cdot \left(\cos \lambda_1 \cdot \cos \phi_2\right)\right) + \color{blue}{\log \left(e^{\sin \lambda_1 \cdot \sin \lambda_2}\right)} \cdot \cos \phi_2}\]

  15. Final simplification0.2

    \[\leadsto \lambda_1 + \tan^{-1}_* \frac{\cos \lambda_2 \cdot \left(\sin \lambda_1 \cdot \cos \phi_2\right) + \sin \left(-\lambda_2\right) \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)}{\left(\cos \phi_1 + \cos \lambda_2 \cdot \left(\cos \phi_2 \cdot \cos \lambda_1\right)\right) + \cos \phi_2 \cdot \log \left(e^{\sin \lambda_1 \cdot \sin \lambda_2}\right)}\]

Reproduce

herbie shell --seed 2021023 
(FPCore (lambda1 lambda2 phi1 phi2)
  :name "Midpoint on a great circle"
  :precision binary64
  (+ lambda1 (atan2 (* (cos phi2) (sin (- lambda1 lambda2))) (+ (cos phi1) (* (cos phi2) (cos (- lambda1 lambda2)))))))