Approximation and interpolation.

TL;DR: A Lanczos-type algorithm that extends the classical Lanczos process for single starting vectors to mul- tiple starting vectors and can handle the most general case of right and left start- ing blocks of arbitrary sizes.

TL;DR: In this paper, the authors consider Farrell sets in terms of their cluster points on the unit disc and show that the set of cluster points of S on T which are not nontangential limits of sequences from S is here too large.

TL;DR: In this paper, the authors present a discussion of the constructive methods for rational approximation developed by Vitushkin in [13] and [14] and present a generalization of this approach to vector-valued functions, in order to obtain results on uniform approximation by analytic functions.