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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 2008 Volume 84, Issue 3, Pages 409–419 (Mi mzm4049)

This article is cited in 1 paper

On the Asymptotics of the Rows of the Padé Table of Analytic Functions with Logarithmic Branch Points

A. P. Starovoitov, N. A. Starovoitova

Francisk Skorina Gomel State University

Abstract: For the functions $f(z)=\sum_{n=0}^\infty z^{l_n}/a_n$, where $l_n$ and $a_n$ are arithmetic progressions and their Padé approximants $\pi_{n,m}(z;f)$, we establish an asymptotics of the decrease of the difference $f(z)-\pi_{n,m}(z;f)$ for the case in which $z\in D=\{z:|z|<1\}$, $m$ is fixed, and $n\to\infty$. In particular, we obtain proximate orders of decrease of best uniform rational approximations to the functions $\ln(1-z)$ and $\operatorname{arctan}z$ in the disk $D_q=\{z:|z|\le q<1\}$.

Keywords: Padé approximant, Padé table, analytic function, logarithmic branch point, arithmetic progression, Hadamard determinant, Vandermonde determinant.

UDC: 517.51, 517.53

Received: 11.05.2007

DOI: 10.4213/mzm4049


 English version:
Mathematical Notes, 2008, 84:3, 379–388

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