double f(double lambda1, double lambda2, double phi1, double phi2) {
double r3848447 = lambda1;
double r3848448 = lambda2;
double r3848449 = r3848447 - r3848448;
double r3848450 = sin(r3848449);
double r3848451 = phi2;
double r3848452 = cos(r3848451);
double r3848453 = r3848450 * r3848452;
double r3848454 = phi1;
double r3848455 = cos(r3848454);
double r3848456 = sin(r3848451);
double r3848457 = r3848455 * r3848456;
double r3848458 = sin(r3848454);
double r3848459 = r3848458 * r3848452;
double r3848460 = cos(r3848449);
double r3848461 = r3848459 * r3848460;
double r3848462 = r3848457 - r3848461;
double r3848463 = atan2(r3848453, r3848462);
return r3848463;
}