Classes of $(\psi, \beta)$-differential functions of complex variable and approximation by linear averages of their Faber series

We introduce the notion of $(\psi, \beta)$-derivative of a function of one complex variable, and define on the basis of this the classes $L_\beta ^{\psi}{\mathfrak N} (G)$  of $(\psi, \beta)$-differentiable analytic functions in a bounded domain $G$. The classes $L_\beta ^{\psi}{\mathfr...

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Bibliographic Details
Date:1992
Main Authors: Stepanec, A.I., Romanyuk, V.S., Степанец, А.И., Романюк, В С.
Format: Article
Language:Russian
Published: Institute of Mathematics, NAS of Ukraine 1992
Online Access:https://umj.imath.kiev.ua/index.php/umj/article/view/8259
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Journal Title:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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Summary:We introduce the notion of $(\psi, \beta)$-derivative of a function of one complex variable, and define on the basis of this the classes $L_\beta ^{\psi}{\mathfrak N} (G)$  of $(\psi, \beta)$-differentiable analytic functions in a bounded domain $G$. The classes $L_\beta ^{\psi}{\mathfrak N} (G)$ consist of the Cauchy-type integrals whose densities $f(\zeta)$ are such that the induced functions $\tilde f(t)$  on the unit circle are periodic functions of classes $L_\beta ^{\psi}{\mathfrak N}$. We consider approximation of functions $f\in L_\beta ^{\psi}{\mathfrak N} (G)$  by algebraic polynomials constructed from their series expansions in Faber polynomials.