double f(double lambda1, double lambda2, double phi1, double phi2) {
double r17085477 = lambda1;
double r17085478 = lambda2;
double r17085479 = r17085477 - r17085478;
double r17085480 = sin(r17085479);
double r17085481 = phi2;
double r17085482 = cos(r17085481);
double r17085483 = r17085480 * r17085482;
double r17085484 = phi1;
double r17085485 = cos(r17085484);
double r17085486 = sin(r17085481);
double r17085487 = r17085485 * r17085486;
double r17085488 = sin(r17085484);
double r17085489 = r17085488 * r17085482;
double r17085490 = cos(r17085479);
double r17085491 = r17085489 * r17085490;
double r17085492 = r17085487 - r17085491;
double r17085493 = atan2(r17085483, r17085492);
return r17085493;
}