double f(double lambda1, double lambda2, double phi1, double phi2) {
double r15515776 = lambda1;
double r15515777 = lambda2;
double r15515778 = r15515776 - r15515777;
double r15515779 = sin(r15515778);
double r15515780 = phi2;
double r15515781 = cos(r15515780);
double r15515782 = r15515779 * r15515781;
double r15515783 = phi1;
double r15515784 = cos(r15515783);
double r15515785 = sin(r15515780);
double r15515786 = r15515784 * r15515785;
double r15515787 = sin(r15515783);
double r15515788 = r15515787 * r15515781;
double r15515789 = cos(r15515778);
double r15515790 = r15515788 * r15515789;
double r15515791 = r15515786 - r15515790;
double r15515792 = atan2(r15515782, r15515791);
return r15515792;
}