size_t dist_rho5D_index(int i_rho, int i_theta, int i_phi, int i_ppara, int i_pperp, int i_time, int i_q, size_t step_6, size_t step_5, size_t step_4, size_t step_3, size_t step_2, size_t step_1)
Internal function calculating the index in the histogram array.