\[\cos^{-1} \left(\sin \phi_1 \cdot \sin \phi_2 + \left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \cos \left(\lambda_1 - \lambda_2\right)\right) \cdot R\]

\cos^{-1} \left(\sin \phi_1 \cdot \sin \phi_2 + \left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \cos \left(\lambda_1 - \lambda_2\right)\right) \cdot R

double f(double R, double lambda1, double lambda2, double phi1, double phi2) {
        double r7981 = phi1;
        double r7982 = sin(r7981);
        double r7983 = phi2;
        double r7984 = sin(r7983);
        double r7985 = r7982 * r7984;
        double r7986 = cos(r7981);
        double r7987 = cos(r7983);
        double r7988 = r7986 * r7987;
        double r7989 = lambda1;
        double r7990 = lambda2;
        double r7991 = r7989 - r7990;
        double r7992 = cos(r7991);
        double r7993 = r7988 * r7992;
        double r7994 = r7985 + r7993;
        double r7995 = acos(r7994);
        double r7996 = R;
        double r7997 = r7995 * r7996;
        return r7997;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (R lambda1 lambda2 phi1 phi2)
  :name "Spherical law of cosines"
  (* (acos (+ (* (sin phi1) (sin phi2)) (* (* (cos phi1) (cos phi2)) (cos (- lambda1 lambda2))))) R))

Backtrace

get-representation: Unknown representation #f		L	C
loop	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	122	4
prepare-points	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	146	0
setup-prog!34	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	67	0
run-improve43	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	339	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28