\[R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)\]
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 r2082237 = R;
double r2082238 = 2.0;
double r2082239 = phi1;
double r2082240 = phi2;
double r2082241 = r2082239 - r2082240;
double r2082242 = r2082241 / r2082238;
double r2082243 = sin(r2082242);
double r2082244 = pow(r2082243, r2082238);
double r2082245 = cos(r2082239);
double r2082246 = cos(r2082240);
double r2082247 = r2082245 * r2082246;
double r2082248 = lambda1;
double r2082249 = lambda2;
double r2082250 = r2082248 - r2082249;
double r2082251 = r2082250 / r2082238;
double r2082252 = sin(r2082251);
double r2082253 = r2082247 * r2082252;
double r2082254 = r2082253 * r2082252;
double r2082255 = r2082244 + r2082254;
double r2082256 = sqrt(r2082255);
double r2082257 = 1.0;
double r2082258 = r2082257 - r2082255;
double r2082259 = sqrt(r2082258);
double r2082260 = atan2(r2082256, r2082259);
double r2082261 = r2082238 * r2082260;
double r2082262 = r2082237 * r2082261;
return r2082262;
}