Order estimates of the best approximations and approximations of Fourier sums of classes of convolutions of periodic functions of not high smoothness in uniform metric

Abstract

We obtain exact for order estimates of best uniform approximations and uniform approximations by Fourier sums of classes of convolutions the periodic functions belong to unit balls of spaces $L_p,1\le p<\infty$, with generating kernel ${\Psi }_{\beta }$, whose absolute values of Fourier coefficients $\psi (k)$ are such that $\sum _{k=1}^{\infty }{\psi }^{p^{\prime }}(k)k^{p^{\prime }-2}<\infty$, $\frac{1}{p}+\frac{1}{p^{\prime }}=1$, and product $\psi (n)n^{\frac{1}{p}}$ can't tend to nought faster than power functions.

arXiv comment20 pages, in Ukrainian

Cited by in corpus (1)

• Order estimates of the best orthogonal trigonometric approximations of classes of convolutions of periodic functions of not high smoothness