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

\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 r1266136 = lambda1;
        double r1266137 = theta;
        double r1266138 = sin(r1266137);
        double r1266139 = delta;
        double r1266140 = sin(r1266139);
        double r1266141 = r1266138 * r1266140;
        double r1266142 = phi1;
        double r1266143 = cos(r1266142);
        double r1266144 = r1266141 * r1266143;
        double r1266145 = cos(r1266139);
        double r1266146 = sin(r1266142);
        double r1266147 = r1266146 * r1266145;
        double r1266148 = r1266143 * r1266140;
        double r1266149 = cos(r1266137);
        double r1266150 = r1266148 * r1266149;
        double r1266151 = r1266147 + r1266150;
        double r1266152 = asin(r1266151);
        double r1266153 = sin(r1266152);
        double r1266154 = r1266146 * r1266153;
        double r1266155 = r1266145 - r1266154;
        double r1266156 = atan2(r1266144, r1266155);
        double r1266157 = r1266136 + r1266156;
        return r1266157;
}

Reproduce

herbie shell --seed 2019142 +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