double f(double lambda1, double lambda2, double phi1, double phi2) {
double r9177521 = lambda1;
double r9177522 = lambda2;
double r9177523 = r9177521 - r9177522;
double r9177524 = sin(r9177523);
double r9177525 = phi2;
double r9177526 = cos(r9177525);
double r9177527 = r9177524 * r9177526;
double r9177528 = phi1;
double r9177529 = cos(r9177528);
double r9177530 = sin(r9177525);
double r9177531 = r9177529 * r9177530;
double r9177532 = sin(r9177528);
double r9177533 = r9177532 * r9177526;
double r9177534 = cos(r9177523);
double r9177535 = r9177533 * r9177534;
double r9177536 = r9177531 - r9177535;
double r9177537 = atan2(r9177527, r9177536);
return r9177537;
}