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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2020 Volume 211, Number 10, Pages 139–156 (Mi sm8634)

This article is cited in 18 papers

Hermite-Padé approximants to the Weyl function and its derivative for discrete measures

V. N. Sorokin

Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow, Russia

Abstract: Hermite-Padé approximants of the second kind to the Weyl function and its derivatives are investigated. The Weyl function is constructed from the orthogonal Meixner polynomials. The limiting distribution of the zeros of the common denominators of these approximants, which are multiple orthogonal polynomials for a discrete measure, is found. It is proved that the limit measure is the unique solution of the equilibrium problem in the theory of the logarithmic potential with an Angelesco matrix. The effect of pushing some zeros off the real axis to some curve in the complex plane is discovered. An explicit form of the limit measure in terms of algebraic functions is given.
Bibliography: 10 titles.

Keywords: Meixner polynomials, equilibrium problems in logarithmic potential theory, Riemann surfaces, algebraic functions.

UDC: 517.53

MSC: 41A21, 42C05

Received: 16.11.2015 and 30.05.2020

DOI: 10.4213/sm8634


 English version:
Sbornik: Mathematics, 2020, 211:10, 1486–1502

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© Steklov Math. Inst. of RAS, 2026