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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 1978 Volume 23, Issue 2, Pages 197–212 (Mi mzm8133)

This article is cited in 25 papers

Approximation by Fourier sums of classes of functions with several bounded derivatives

È. M. Galeev

M. V. Lomonosov Moscow State University

Abstract: An ordered estimate is obtained for the approximation by Fourier sums, in the metric $\widetilde{\mathscr L}$, $q=(q_1,\dots,q_n)$, $1<q_<\infty$, $j=1,\dots,n$, of classes of periodic functions of several variables with zero means with respect to all their arguments, having $m$ mixed derivatives of order $\alpha^1,\dots,\alpha_i^m$, $\alpha^i\in R^n$. which are bounded in the metrics of$\widetilde{\mathscr L}_{p^1},\dots,\widetilde{\mathscr L}_{p^m}$, $p^i=(p_1^i,\dots,p_n^i)$, $1<p_j^i<\infty$, $i=1,\dots,m$, $j=1,\dots,n$ by the constants $\beta_1,\dots,\beta_m$, respectively.

UDC: 517.5

Received: 10.06.1976


 English version:
Mathematical Notes, 1978, 23:2, 109–117

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