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This article is cited in 1 scientific paper (total in 1 paper)
Convergence of Trigonometric Fourier Series of Functions with a Constraint on the Fractality of Their Graphs
M. L. Gridnev Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg
Abstract:
For a function $f$ continuous on a closed interval, its modulus of fractality $\nu(f,\varepsilon)$ is defined as the function that maps any $\varepsilon>0$ to the smallest number of squares of size $\varepsilon$ that cover the graph of $f$. The following condition for the uniform convergence of the Fourier series of $f$ is obtained in terms of the modulus of fractality and the modulus of continuity $\omega(f,\delta)$: if
$$
\omega (f,\pi/n) \ln\bigg(\frac{\nu(f,\pi/n)}{n}\bigg) \longrightarrow 0\ \ \ as \ n\longrightarrow+\infty,
$$
then the Fourier series of $f$ converges uniformly. This condition refines the known Dini–Lipschitz test. In addition, for the growth order of the partial sums $S_n(f,x)$ of a continuous function $f$, we derive an estimate that is uniform in $x\in[0,2\pi]$:
$$
S_n(f,x)=o\bigg( \ln \bigg(\frac{\nu (f,\pi / n)}{n}\bigg)\bigg).
$$
The optimality of this estimate is shown.
Keywords:
trigonometric Fourier series, uniform convergence, fractal dimension.
Received: 31.08.2018 Revised: 28.10.2018 Accepted: 05.11.2018
Citation:
M. L. Gridnev, “Convergence of Trigonometric Fourier Series of Functions with a Constraint on the Fractality of Their Graphs”, Trudy Inst. Mat. i Mekh. UrO RAN, 24, no. 4, 2018, 104–109; Proc. Steklov Inst. Math. (Suppl.), 308, suppl. 1 (2020), S106–S111
Linking options:
https://www.mathnet.ru/eng/timm1578 https://www.mathnet.ru/eng/timm/v24/i4/p104
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Abstract page: | 256 | Full-text PDF : | 76 | References: | 43 | First page: | 2 |
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