\[\lambda_1 + \tan^{-1}_* \frac{\left(\sin theta \cdot \sin delta\right) \cdot \cos \phi_1}{\cos delta - \sin \phi_1 \cdot \sin \left(\sin^{-1} \left(\sin \phi_1 \cdot \cos delta + \left(\cos \phi_1 \cdot \sin delta\right) \cdot \cos theta\right)\right)}\]

\lambda_1 + \tan^{-1}_* \frac{\left(\sin theta \cdot \sin delta\right) \cdot \cos \phi_1}{\cos delta - \sin \phi_1 \cdot \sin \left(\sin^{-1} \left(\sin \phi_1 \cdot \cos delta + \left(\cos \phi_1 \cdot \sin delta\right) \cdot \cos theta\right)\right)}

double f(double lambda1, double phi1, double __attribute__((unused)) phi2, double delta, double theta) {
        double r2309490 = lambda1;
        double r2309491 = theta;
        double r2309492 = sin(r2309491);
        double r2309493 = delta;
        double r2309494 = sin(r2309493);
        double r2309495 = r2309492 * r2309494;
        double r2309496 = phi1;
        double r2309497 = cos(r2309496);
        double r2309498 = r2309495 * r2309497;
        double r2309499 = cos(r2309493);
        double r2309500 = sin(r2309496);
        double r2309501 = r2309500 * r2309499;
        double r2309502 = r2309497 * r2309494;
        double r2309503 = cos(r2309491);
        double r2309504 = r2309502 * r2309503;
        double r2309505 = r2309501 + r2309504;
        double r2309506 = asin(r2309505);
        double r2309507 = sin(r2309506);
        double r2309508 = r2309500 * r2309507;
        double r2309509 = r2309499 - r2309508;
        double r2309510 = atan2(r2309498, r2309509);
        double r2309511 = r2309490 + r2309510;
        return r2309511;
}

Reproduce

herbie shell --seed 2019132 +o rules:numerics
(FPCore (lambda1 phi1 phi2 delta theta)
  :name "Destination given bearing on a great circle"
  (+ lambda1 (atan2 (* (* (sin theta) (sin delta)) (cos phi1)) (- (cos delta) (* (sin phi1) (sin (asin (+ (* (sin phi1) (cos delta)) (* (* (cos phi1) (sin delta)) (cos theta))))))))))

Timeout in 10.0m

Reproduce