double f(double lambda1, double lambda2, double phi1, double phi2) {
double r2911084 = lambda1;
double r2911085 = lambda2;
double r2911086 = r2911084 - r2911085;
double r2911087 = sin(r2911086);
double r2911088 = phi2;
double r2911089 = cos(r2911088);
double r2911090 = r2911087 * r2911089;
double r2911091 = phi1;
double r2911092 = cos(r2911091);
double r2911093 = sin(r2911088);
double r2911094 = r2911092 * r2911093;
double r2911095 = sin(r2911091);
double r2911096 = r2911095 * r2911089;
double r2911097 = cos(r2911086);
double r2911098 = r2911096 * r2911097;
double r2911099 = r2911094 - r2911098;
double r2911100 = atan2(r2911090, r2911099);
return r2911100;
}