double f(double lambda1, double lambda2, double phi1, double phi2) {
double r16251642 = lambda1;
double r16251643 = lambda2;
double r16251644 = r16251642 - r16251643;
double r16251645 = sin(r16251644);
double r16251646 = phi2;
double r16251647 = cos(r16251646);
double r16251648 = r16251645 * r16251647;
double r16251649 = phi1;
double r16251650 = cos(r16251649);
double r16251651 = sin(r16251646);
double r16251652 = r16251650 * r16251651;
double r16251653 = sin(r16251649);
double r16251654 = r16251653 * r16251647;
double r16251655 = cos(r16251644);
double r16251656 = r16251654 * r16251655;
double r16251657 = r16251652 - r16251656;
double r16251658 = atan2(r16251648, r16251657);
return r16251658;
}