double f(double lambda1, double lambda2, double phi1, double phi2) {
double r10710122 = lambda1;
double r10710123 = lambda2;
double r10710124 = r10710122 - r10710123;
double r10710125 = sin(r10710124);
double r10710126 = phi2;
double r10710127 = cos(r10710126);
double r10710128 = r10710125 * r10710127;
double r10710129 = phi1;
double r10710130 = cos(r10710129);
double r10710131 = sin(r10710126);
double r10710132 = r10710130 * r10710131;
double r10710133 = sin(r10710129);
double r10710134 = r10710133 * r10710127;
double r10710135 = cos(r10710124);
double r10710136 = r10710134 * r10710135;
double r10710137 = r10710132 - r10710136;
double r10710138 = atan2(r10710128, r10710137);
return r10710138;
}