2018
Том 70
№ 11

All Issues

On the Best Polynomial Approximations of $2π$-Periodic Functions and Exact Values of $n$-Widths of Functional Classes in the Space $L_2$

Vakarchuk S. B.

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Abstract

To solve extremal problems of approximation theory in the space $L_2$, we use τ-moduli introduced by Ivanov. We determine the exact values of constants in Jackson-type inequalities and the exact values of $n$-widths of functional classes determined by these moduli.

English version (Springer): Ukrainian Mathematical Journal 54 (2002), no. 12, pp 1943–1957.

Citation Example: Vakarchuk S. B. On the Best Polynomial Approximations of $2π$-Periodic Functions and Exact Values of $n$-Widths of Functional Classes in the Space $L_2$ // Ukr. Mat. Zh. - 2002. - 54, № 12. - pp. 1603-1615.

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