double f(double lambda1, double lambda2, double phi1, double phi2) {
double r1686049 = lambda1;
double r1686050 = lambda2;
double r1686051 = r1686049 - r1686050;
double r1686052 = sin(r1686051);
double r1686053 = phi2;
double r1686054 = cos(r1686053);
double r1686055 = r1686052 * r1686054;
double r1686056 = phi1;
double r1686057 = cos(r1686056);
double r1686058 = sin(r1686053);
double r1686059 = r1686057 * r1686058;
double r1686060 = sin(r1686056);
double r1686061 = r1686060 * r1686054;
double r1686062 = cos(r1686051);
double r1686063 = r1686061 * r1686062;
double r1686064 = r1686059 - r1686063;
double r1686065 = atan2(r1686055, r1686064);
return r1686065;
}