Degree of approximation by means of hexagonal Fourier series

Authors: ALİ GÜVEN

Abstract: Let $f$ be a continuous function which is periodic with respect to the hexagon lattice, and let $A$ be a lower triangular infinite matrix of nonnegative real numbers with nonincreasing rows. The degree of approximation of the function $f$ by matrix means $T_{n}^{\left( A\right) }\left( f\right) $ of its hexagonal Fourier series is estimated in terms of the modulus of continuity of $f.$

Keywords: Hexagonal domain, hexagonal Fourier series, Hölder class, matrix mean

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