Local and Global Approximation Theorems for Positive Linear Operators

In this paper we bridge local and global approximation theorems for positive linear operators via Ditzian–Totik moduliω2φ(f,δ) of second order whereby the step-weightsφare functions whose squares are concave. Both direct and converse theorems are derived. In particular we investigate the situation f...

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Vydané v:Journal of approximation theory Ročník 94; číslo 3; s. 396 - 419
Hlavný autor: Felten, Michael
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: Elsevier Inc 01.09.1998
ISSN:0021-9045, 1096-0430
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Popis
Shrnutí:In this paper we bridge local and global approximation theorems for positive linear operators via Ditzian–Totik moduliω2φ(f,δ) of second order whereby the step-weightsφare functions whose squares are concave. Both direct and converse theorems are derived. In particular we investigate the situation for exponential-type and Bernstein-type operators.
ISSN:0021-9045
1096-0430
DOI:10.1006/jath.1998.3212