Multipoint Schur algorithm and orthogonal rational functions: convergence properties, I

L. Baratchart, S. Kupin, V. Lunot, M. Olivi

Published 2008-12-10, updated 2010-02-11Version 3

Classical Schur analysis is intimately connected to the theory of orthogonal polynomials on the circle [Simon, 2005]. We investigate here the connection between multipoint Schur analysis and orthogonal rational functions. Specifically, we study the convergence of the Wall rational functions via the development of a rational analogue to the Szeg\H o theory, in the case where the interpolation points may accumulate on the unit circle. This leads us to generalize results from [Khrushchev,2001], [Bultheel et al., 1999], and yields asymptotics of a novel type.