3 papers
math.FA2026
Extremal representations of functions of matrices and applications to multivariate prediction
Michael Frank, Lutz Klotz, Andreas Lasarow
Motivated by two seminal results of multivariate prediction theory by Helson and Lowdenslager and by Wiener and Masani we prove extremal representations of functions of matrices an…
math.NA2017
Orthogonal Rational Functions on the Unit Circle with Prescribed Poles not on the Unit Circle
Adhemar Bultheel, Ruyman Cruz-Barroso, Andreas Lasarow
Orthogonal rational functions (ORF) on the unit circle generalize orthogonal polynomials (poles at infinity) and Laurent polynomials (poles at zero and infinity). In this paper we…
math.FA2009
Shift Operators Contained in Contractions, Pseudocontinuable Schur Functions and Orthogonal Systems on the Unit Circle
Vladimir K. Dubovoy, Bernd Fritzsche, Bernd Kirstein
The main aim of this paper is to establish the connection between well-known criteria for the pseudocontinuability of a non-inner Schur function Theta in the unit disk. In a canoni…