Use the --timeout flag to change the timeout.
R \cdot \sqrt{\left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) \cdot \left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) + \left(\phi_1 - \phi_2\right) \cdot \left(\phi_1 - \phi_2\right)}double f(double R, double lambda1, double lambda2, double phi1, double phi2) {
double r793578 = R;
double r793579 = lambda1;
double r793580 = lambda2;
double r793581 = r793579 - r793580;
double r793582 = phi1;
double r793583 = phi2;
double r793584 = r793582 + r793583;
double r793585 = 2.0;
double r793586 = r793584 / r793585;
double r793587 = cos(r793586);
double r793588 = r793581 * r793587;
double r793589 = r793588 * r793588;
double r793590 = r793582 - r793583;
double r793591 = r793590 * r793590;
double r793592 = r793589 + r793591;
double r793593 = sqrt(r793592);
double r793594 = r793578 * r793593;
return r793594;
}
herbie shell --seed 2020059
(FPCore (R lambda1 lambda2 phi1 phi2)
:name "Equirectangular approximation to distance on a great circle"
:precision binary64
(* R (sqrt (+ (* (* (- lambda1 lambda2) (cos (/ (+ phi1 phi2) 2))) (* (- lambda1 lambda2) (cos (/ (+ phi1 phi2) 2)))) (* (- phi1 phi2) (- phi1 phi2))))))