Abstract:
Rational approximations to the function zα, α∈R∖Z, were studied by Newman, Gonchar, Bulanov, Vyacheslavov, Andersson, Stahl, and others. The present paper deals with the order of best rational approximations to this function in a domain with zero external angle and vertex at the point z=0. In particular, the obtained results show that the conditions imposed on the boundary of the domain in the Jackson-type inequality proved by the author in 2001 for the best rational approximations in Smirnov spaces cannot be weakened significantly.
Keywords:
best uniform rational approximation, polynomial approximation, Smirnov space, analytic function, rational function, rectifiable Jordan boundary, Lavrentiev curve.
Citation:
A. A. Pekarskii, “Approximation to the Function zα by Rational Fractions in a Domain with Zero External Angle”, Mat. Zametki, 91:5 (2012), 761–772; Math. Notes, 91:5 (2012), 714–724
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\by A.~A.~Pekarskii
\paper Approximation to the Function ~$z^{\alpha}$ by Rational Fractions in a Domain with Zero External Angle
\jour Mat. Zametki
\yr 2012
\vol 91
\issue 5
\pages 761--772
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\jour Math. Notes
\yr 2012
\vol 91
\issue 5
\pages 714--724
\crossref{https://doi.org/10.1134/S0001434612050136}
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Linking options:
https://www.mathnet.ru/eng/mzm8759
https://doi.org/10.4213/mzm8759
https://www.mathnet.ru/eng/mzm/v91/i5/p761
This publication is cited in the following 5 articles:
P. G. Potseiko, Y. A. Rovba, “On Estimates of Uniform Approximations by Rational Fourier–Chebyshev Integral Operators for a Certain Choice of Poles”, Math. Notes, 113:6 (2023), 815–830
Yipei Zhang, Guixiang Wang, 2021 2nd International Conference on Artificial Intelligence and Information Systems, 2021, 1
Wang G., Shen Ch., Wang Ya., “Approximation of Fuzzy Numbers By Using Multi-Knots Piecewise Linear Fuzzy Numbers”, J. Intell. Fuzzy Syst., 39:3 (2020), 3597–3615
Chenjie Shen, Guixiang Wang, Yifeng Xu, Advances in Intelligent Systems and Computing, 1074, Advances in Natural Computation, Fuzzy Systems and Knowledge Discovery, 2020, 686
G. Wang, J. Li, “Approximations of fuzzy numbers by step type fuzzy numbers”, Fuzzy Sets and Systems, 310 (2017), 47–59