On the degree of the approximation of functions of several variables by linear positive operators of finite rank

1993 ◽  
Vol 53 (1) ◽  
pp. 3-11 ◽  
Author(s):  
R. K. Vasil'ev
2007 ◽  
Vol 117 (3) ◽  
pp. 387-399 ◽  
Author(s):  
Fatma Taşdelen ◽  
Ali Olgun ◽  
Gülen Başcanbaz-Tunca

2020 ◽  
Vol 28 (3) ◽  
pp. 255-265
Author(s):  
Fuat Usta

AbstractIn this manuscript, linear and positive operators described on bounded and unbounded intervals that fix the function sets {1, φ} and {1, φ2} such that φ ∈ C[0, 1] are presented. Then we present different types of operators by choosing different functions and values. Finally, Voronovskaya type theorems are given for this newly defined sequences of linear and positive operators.


2017 ◽  
Vol 26 (2) ◽  
pp. 137-143
Author(s):  
DAN BARBOSU

The goal of the paper is to present some results concerning the approximation of convex functions by linear positive operators. First, one recalls some results concerning the univariate real valued convex functions. Next, one presents the notion of higher order convexity introduced by Popoviciu [Popoviciu, T., Sur quelques propri´et´ees des fonctions d’une ou deux variable r´eelles, PhD Thesis, La Faculte des Sciences de Paris, 1933 (June)] . The Popoviciu’s famous theorem for the representation of linear functionals associated to convex functions of m−th order (with the proof of author) is also presented. Finally, applications of the convexity to study the monotonicity of sequences of some linear positive operators and also mean value theorems for the remainder term of some approximation formulas based on linear positive operators are presented.


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