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Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy, 2020, Volume 7, Issue 3, Pages 481–489
DOI: https://doi.org/10.21638/spbu01.2020.310
(Mi vspua171)
 

This article is cited in 1 scientific paper (total in 1 paper)

MATHEMATICS

Approximation by entire functions on a countable set of continuums

O. V. Silvanovicha, N. A. Shirokovb

a St. Petersburg Mining University, 2, 21-ia liniia V. O., St.Petersburg, 199106, Russian Federation
b St. Petersburg State University, 7-9, Universitetskaya nab., St. Petersburg, 199034, Russian Federation
Full-text PDF (316 kB) Citations (1)
Abstract: We consider a problem of approximation by entire functions of exponential type of functions defined on a countable set $E$ of continuums $G_n$, $E = \bigcup_{n\in\mathbb{Z}} G_n$. We assume that all $G_n$ are pairwise disjoint and are situated near the real axis. We assume too that all $G_n$ are commensurable in a sense and have uniformly smooth boundaries. A function f is defined independantly on each $G_n$ and is bounded on $E$ and $f^{(r)}$ has a module of continuity $\omega$ which satisfies a condition $\int_0^x\omega(t)/t dt+x\int_x^\infty\omega(t)/t^2dt\leqslant c\omega(x)$. Then we construct an entire function $F_\sigma$ of exponential type $\leqslant\sigma$ such that we have the following estimate of approximation of the function $f$ by functions $F_\sigma$: $|f(z) - F_\sigma(z)| \leqslant c_f\sigma^{-r} \omega(\sigma^{-r}), z \in \mathbb{Z}, \sigma \leqslant 1$.
Keywords: Holder classes, approximation, entire functions of exponential type.
Funding agency Grant number
Russian Foundation for Basic Research 20-01-00209
The work is supported by Russian Foundation for Basic Research (grant no. 20-01-00209).
Received: 18.02.2019
Revised: 16.03.2020
Accepted: 19.03.2020
English version:
Vestnik St. Petersburg University, Mathematics, 2020, Volume 7, Issue 3, Pages 329–335
DOI: https://doi.org/10.1134/S1063454120030139
Document Type: Article
UDC: 517.537
MSC: 30E10
Language: Russian
Citation: O. V. Silvanovich, N. A. Shirokov, “Approximation by entire functions on a countable set of continuums”, Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy, 7:3 (2020), 481–489; Vestn. St. Petersbg. Univ., Math., 7:3 (2020), 329–335
Citation in format AMSBIB
\Bibitem{SilShi20}
\by O.~V.~Silvanovich, N.~A.~Shirokov
\paper Approximation by entire functions on a countable set of continuums
\jour Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy
\yr 2020
\vol 7
\issue 3
\pages 481--489
\mathnet{http://mi.mathnet.ru/vspua171}
\crossref{https://doi.org/10.21638/spbu01.2020.310}
\transl
\jour Vestn. St. Petersbg. Univ., Math.
\yr 2020
\vol 7
\issue 3
\pages 329--335
\crossref{https://doi.org/10.1134/S1063454120030139}
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  • This publication is cited in the following 1 articles:
    Citing articles in Google Scholar: Russian citations, English citations
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    Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy
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