double f(double lambda1, double lambda2, double phi1, double phi2) {
double r21945512 = lambda1;
double r21945513 = lambda2;
double r21945514 = r21945512 - r21945513;
double r21945515 = sin(r21945514);
double r21945516 = phi2;
double r21945517 = cos(r21945516);
double r21945518 = r21945515 * r21945517;
double r21945519 = phi1;
double r21945520 = cos(r21945519);
double r21945521 = sin(r21945516);
double r21945522 = r21945520 * r21945521;
double r21945523 = sin(r21945519);
double r21945524 = r21945523 * r21945517;
double r21945525 = cos(r21945514);
double r21945526 = r21945524 * r21945525;
double r21945527 = r21945522 - r21945526;
double r21945528 = atan2(r21945518, r21945527);
return r21945528;
}