double f(double lambda1, double lambda2, double phi1, double phi2) {
double r16546677 = lambda1;
double r16546678 = lambda2;
double r16546679 = r16546677 - r16546678;
double r16546680 = sin(r16546679);
double r16546681 = phi2;
double r16546682 = cos(r16546681);
double r16546683 = r16546680 * r16546682;
double r16546684 = phi1;
double r16546685 = cos(r16546684);
double r16546686 = sin(r16546681);
double r16546687 = r16546685 * r16546686;
double r16546688 = sin(r16546684);
double r16546689 = r16546688 * r16546682;
double r16546690 = cos(r16546679);
double r16546691 = r16546689 * r16546690;
double r16546692 = r16546687 - r16546691;
double r16546693 = atan2(r16546683, r16546692);
return r16546693;
}