2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/163716First, an abstract scheme of constructing biorthogonal rational systems related to some interpolation problems is proposed. We also present a modification of the famous step-by-step process of solving the Nevanlinna-Pick problems for Nevanlinna functions. The process in question gives rise to three-term recurrence relations with coefficients depending on the spectral parameter. These relations can be rewritten in the matrix form by means of two Jacobi matrices. As a result, a convergence theorem for multipoint Padé approximants to Nevanlinna functions is proved.18 pagesClassical Analysis and ODEsComplex VariablesSpectral Theory30E05, 41A21, 47B36 (Primary); 30E10, 40A15, 47A57 (Secondary)text