double f(double lambda1, double lambda2, double phi1, double phi2) {
double r3619509 = lambda1;
double r3619510 = lambda2;
double r3619511 = r3619509 - r3619510;
double r3619512 = sin(r3619511);
double r3619513 = phi2;
double r3619514 = cos(r3619513);
double r3619515 = r3619512 * r3619514;
double r3619516 = phi1;
double r3619517 = cos(r3619516);
double r3619518 = sin(r3619513);
double r3619519 = r3619517 * r3619518;
double r3619520 = sin(r3619516);
double r3619521 = r3619520 * r3619514;
double r3619522 = cos(r3619511);
double r3619523 = r3619521 * r3619522;
double r3619524 = r3619519 - r3619523;
double r3619525 = atan2(r3619515, r3619524);
return r3619525;
}