\[R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)\]
R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)double f(double R, double lambda1, double lambda2, double phi1, double phi2) {
double r697707 = R;
double r697708 = 2.0;
double r697709 = phi1;
double r697710 = phi2;
double r697711 = r697709 - r697710;
double r697712 = r697711 / r697708;
double r697713 = sin(r697712);
double r697714 = pow(r697713, r697708);
double r697715 = cos(r697709);
double r697716 = cos(r697710);
double r697717 = r697715 * r697716;
double r697718 = lambda1;
double r697719 = lambda2;
double r697720 = r697718 - r697719;
double r697721 = r697720 / r697708;
double r697722 = sin(r697721);
double r697723 = r697717 * r697722;
double r697724 = r697723 * r697722;
double r697725 = r697714 + r697724;
double r697726 = sqrt(r697725);
double r697727 = 1.0;
double r697728 = r697727 - r697725;
double r697729 = sqrt(r697728);
double r697730 = atan2(r697726, r697729);
double r697731 = r697708 * r697730;
double r697732 = r697707 * r697731;
return r697732;
}