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JOURNALS // Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya // Archive

Izv. RAN. Ser. Mat., 2015 Volume 79, Issue 6, Pages 125–144 (Mi im8374)

This article is cited in 1 paper

Nuttall's integral equation and Bernshtein's asymptotic formula for a complex weight

N. R. Ikonomova, R. K. Kovachevaa, S. P. Suetinb

a Institute of Mathematics and Informatics, Bulgarian Academy of Sciences
b Steklov Mathematical Institute of Russian Academy of Sciences

Abstract: We obtain Nuttall's integral equation provided that the corresponding complex-valued function $\sigma(x)$ does not vanish and belongs to the Dini–Lipschitz class. Using this equation, we obtain a complex analogue of Bernshtein's classical asymptotic formulae for polynomials orthogonal on the closed unit interval $\Delta=[-1,1]$ with respect to a complex-valued weight $h(x)=\sigma(x)/\sqrt{1-x^2}$.

Keywords: orthogonal polynomials, Padé polynomials, strong asymptotics, Bernshtein's formula, Nuttall's method.

UDC: 517.53

MSC: 30B70, 33D45, 41A21, 41A25, 41A60, 42C05

Received: 01.04.2015

DOI: 10.4213/im8374


 English version:
Izvestiya: Mathematics, 2015, 79:6, 1215–1234

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