\[R \cdot \left(2 \cdot \tan^{-1}_* \frac{\sqrt{{\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)}}{\sqrt{1 - \left({\left(\sin \left(\frac{\phi_1 - \phi_2}{2}\right)\right)}^{2} + \left(\left(\cos \phi_1 \cdot \cos \phi_2\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right) \cdot \sin \left(\frac{\lambda_1 - \lambda_2}{2}\right)\right)}}\right)\]
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 r6861114 = R;
double r6861115 = 2.0;
double r6861116 = phi1;
double r6861117 = phi2;
double r6861118 = r6861116 - r6861117;
double r6861119 = r6861118 / r6861115;
double r6861120 = sin(r6861119);
double r6861121 = pow(r6861120, r6861115);
double r6861122 = cos(r6861116);
double r6861123 = cos(r6861117);
double r6861124 = r6861122 * r6861123;
double r6861125 = lambda1;
double r6861126 = lambda2;
double r6861127 = r6861125 - r6861126;
double r6861128 = r6861127 / r6861115;
double r6861129 = sin(r6861128);
double r6861130 = r6861124 * r6861129;
double r6861131 = r6861130 * r6861129;
double r6861132 = r6861121 + r6861131;
double r6861133 = sqrt(r6861132);
double r6861134 = 1.0;
double r6861135 = r6861134 - r6861132;
double r6861136 = sqrt(r6861135);
double r6861137 = atan2(r6861133, r6861136);
double r6861138 = r6861115 * r6861137;
double r6861139 = r6861114 * r6861138;
return r6861139;
}