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On approximation of functions by algebraic polynomials in Hölder spaces
Author(s) -
Kolomoitsev Yurii,
Lomako Tetiana,
Prestin Jürgen
Publication year - 2016
Publication title -
mathematische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 50
eISSN - 1522-2616
pISSN - 0025-584X
DOI - 10.1002/mana.201500204
Subject(s) - mathematics , converse , smoothness , algebraic number , inverse , bernstein polynomial , polynomial , pure mathematics , mathematical analysis , geometry
We study approximation of functions by algebraic polynomials in the Hölder spaces corresponding to the generalized Jacobi translation and the Ditzian–Totik moduli of smoothness. By using modifications of the classical moduli of smoothness, we give improvements of the direct and inverse theorems of approximation and prove the criteria of the precise order of decrease of the best approximation in these spaces. Moreover, we obtain strong converse inequalities for some methods of approximation of functions. As an example, we consider approximation by the Durrmeyer–Bernstein polynomial operators.