Calculate the tail length from number of draws and relative efficiency r_eff. See Appendix H in Vehtari et al. (2024). This function is used internally and is exported to be available for other packages.
ps_tail_length(ndraws, r_eff, ...)number of draws
relative efficiency
unused
tail length
Other helper-functions:
ps_convergence_rate(),
ps_khat_threshold(),
ps_min_ss()