Permutation method of ladder synthesis, rational interpolation, and Zolotarev (elliptic) filters

Lin, Tokad, and Szentirmai have discussed in this TRANSACTIONS an algorithm proposed by the author for the synthesis of ladders. In this correspondence, details are given on the relations of this algorithm with rational interpolation, on the pass band case, and on the remarkable case of Zolotarëv (elliptic) filters.