double f(double lambda1, double lambda2, double phi1, double phi2) {
double r3147213 = lambda1;
double r3147214 = lambda2;
double r3147215 = r3147213 - r3147214;
double r3147216 = sin(r3147215);
double r3147217 = phi2;
double r3147218 = cos(r3147217);
double r3147219 = r3147216 * r3147218;
double r3147220 = phi1;
double r3147221 = cos(r3147220);
double r3147222 = sin(r3147217);
double r3147223 = r3147221 * r3147222;
double r3147224 = sin(r3147220);
double r3147225 = r3147224 * r3147218;
double r3147226 = cos(r3147215);
double r3147227 = r3147225 * r3147226;
double r3147228 = r3147223 - r3147227;
double r3147229 = atan2(r3147219, r3147228);
return r3147229;
}