\[R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)\]
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 r2349278 = R;
double r2349279 = 2.0;
double r2349280 = phi1;
double r2349281 = phi2;
double r2349282 = r2349280 - r2349281;
double r2349283 = r2349282 / r2349279;
double r2349284 = sin(r2349283);
double r2349285 = pow(r2349284, r2349279);
double r2349286 = cos(r2349280);
double r2349287 = cos(r2349281);
double r2349288 = r2349286 * r2349287;
double r2349289 = lambda1;
double r2349290 = lambda2;
double r2349291 = r2349289 - r2349290;
double r2349292 = r2349291 / r2349279;
double r2349293 = sin(r2349292);
double r2349294 = r2349288 * r2349293;
double r2349295 = r2349294 * r2349293;
double r2349296 = r2349285 + r2349295;
double r2349297 = sqrt(r2349296);
double r2349298 = 1.0;
double r2349299 = r2349298 - r2349296;
double r2349300 = sqrt(r2349299);
double r2349301 = atan2(r2349297, r2349300);
double r2349302 = r2349279 * r2349301;
double r2349303 = r2349278 * r2349302;
return r2349303;
}