double f(double lambda1, double lambda2, double phi1, double phi2) {
double r15660448 = lambda1;
double r15660449 = lambda2;
double r15660450 = r15660448 - r15660449;
double r15660451 = sin(r15660450);
double r15660452 = phi2;
double r15660453 = cos(r15660452);
double r15660454 = r15660451 * r15660453;
double r15660455 = phi1;
double r15660456 = cos(r15660455);
double r15660457 = sin(r15660452);
double r15660458 = r15660456 * r15660457;
double r15660459 = sin(r15660455);
double r15660460 = r15660459 * r15660453;
double r15660461 = cos(r15660450);
double r15660462 = r15660460 * r15660461;
double r15660463 = r15660458 - r15660462;
double r15660464 = atan2(r15660454, r15660463);
return r15660464;
}