Quasiconvex uniform-convergence factors for Fourier series of functions with a given modulus of continuity

1970 ◽  
Vol 8 (5) ◽  
pp. 817-819 ◽  
Author(s):  
S. A. Telyakovskii
Keyword(s):  
Fourier Series ◽  
Uniform Convergence ◽  
Modulus Of Continuity ◽  
Series Of Functions

Uniform and 𝐿-Convergence of Logarithmic Means of Double Walsh–Fourier Series

2005 ◽  
Vol 12 (1) ◽  
pp. 75-88
Author(s):  
György Gát ◽  
Ushangi Goginava
Keyword(s):  
Fourier Series ◽  
Function Space ◽  
Modulus Of Continuity ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Two Dimensional ◽  
Logarithmic Means ◽  
Convergence And Divergence ◽  
Necessary And Sufficient ◽  
Series Of Functions

Abstract We discuss some convergence and divergence properties of twodimensional (Nörlund) logarithmic means of two-dimensional Walsh–Fourier series of functions both in the uniform and in the Lebesgue norm. We give necessary and sufficient conditions for the convergence regarding the modulus of continuity of the function, and also the function space.

A SUMMABILITY METHOD FOR FOURIER SERIES OF FUNCTIONS OF GENERALIZED BOUNDED VARIATION

Analysis ◽  
1997 ◽  
Vol 17 (2-3) ◽  
pp. 287-300
Author(s):  
LAWRENCE A. D'ANTONIO ◽  
DANIEL WATERMAN
Keyword(s):  
Fourier Series ◽  
Bounded Variation ◽  
Summability Method ◽  
Series Of Functions

The study of the fourier series of functions defined on moran fractals

1997 ◽  
Vol 13 (2) ◽  
pp. 158-166
Author(s):  
Jinrong Liang ◽  
Fuyao Ren
Keyword(s):  
Fourier Series ◽  
Series Of Functions

Fourier series of functions with a non-summable derivative

2009 ◽  
Vol 73 (2) ◽  
pp. 301-318
Author(s):  
Sergei F Lukomskii
Keyword(s):  
Fourier Series ◽  
Series Of Functions

scholarly journals Pointwise and Uniform Convergence of Fourier Extensions

2019 ◽  
Vol 52 (1) ◽  
pp. 139-175
Author(s):  
Marcus Webb ◽  
Vincent Coppé ◽  
Daan Huybrechs
Keyword(s):  
Fourier Series ◽  
Uniform Convergence ◽  
Pointwise Convergence ◽  
Gibbs Phenomenon ◽  
Lebesgue Function ◽  
Bernstein Type ◽  
Legendre Series ◽  
The Best Approximation ◽  
Open Questions ◽  
Algebraic Order

AbstractFourier series approximations of continuous but nonperiodic functions on an interval suffer the Gibbs phenomenon, which means there is a permanent oscillatory overshoot in the neighborhoods of the endpoints. Fourier extensions circumvent this issue by approximating the function using a Fourier series that is periodic on a larger interval. Previous results on the convergence of Fourier extensions have focused on the error in the $$L^2$$ L 2 norm, but in this paper we analyze pointwise and uniform convergence of Fourier extensions (formulated as the best approximation in the $$L^2$$ L 2 norm). We show that the pointwise convergence of Fourier extensions is more similar to Legendre series than classical Fourier series. In particular, unlike classical Fourier series, Fourier extensions yield pointwise convergence at the endpoints of the interval. Similar to Legendre series, pointwise convergence at the endpoints is slower by an algebraic order of a half compared to that in the interior. The proof is conducted by an analysis of the associated Lebesgue function, and Jackson- and Bernstein-type theorems for Fourier extensions. Numerical experiments are provided. We conclude the paper with open questions regarding the regularized and oversampled least squares interpolation versions of Fourier extensions.

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