Sur certains sous-ensembles de , on caractérise les fonctions de classe , les fonctions analytiques et des fonctions de type Gevrey, par leurs distances aux polynômes dans ou dans l’espace des fonctions continues.
We introduce modified -Bernstein-Durrmeyer operators. We discuss approximation properties for these operators based on Korovkin type approximation theorem and compute the order of convergence using usual modulus of continuity. We also study the local approximation property of the sequence of positive linear operators and compute the rate of convergence for the function belonging to the class .
In the paper, we discuss convergence properties and Voronovskaja type theorem for bivariate -Bernstein polynomials for a function analytic in the polydisc for arbitrary fixed . We give quantitative Voronovskaja type estimates for the bivariate -Bernstein polynomials for . In the univariate case the similar results were obtained by S. Ostrovska: -Bernstein polynomials and their iterates. J. Approximation Theory 123 (2003), 232–255. and S. G. Gal: Approximation by Complex Bernstein and Convolution...