double f(double lambda1, double lambda2, double phi1, double phi2) {
double r3731919 = lambda1;
double r3731920 = lambda2;
double r3731921 = r3731919 - r3731920;
double r3731922 = sin(r3731921);
double r3731923 = phi2;
double r3731924 = cos(r3731923);
double r3731925 = r3731922 * r3731924;
double r3731926 = phi1;
double r3731927 = cos(r3731926);
double r3731928 = sin(r3731923);
double r3731929 = r3731927 * r3731928;
double r3731930 = sin(r3731926);
double r3731931 = r3731930 * r3731924;
double r3731932 = cos(r3731921);
double r3731933 = r3731931 * r3731932;
double r3731934 = r3731929 - r3731933;
double r3731935 = atan2(r3731925, r3731934);
return r3731935;
}