On a family of linear and positive operators in weighted spaces.
Chebyshevian box splines were introduced in [5]. The purpose of this paper is to show some new properties of them in the case when the weight functions are of the form , where the functions are periodic functions of one variable. Then we consider the problem of approximation of continuous functions by Chebyshevian box splines.
A characterization of a generalized order of analytic functions of several complex variables by means of polynomial approximation and interpolation is established.
In this paper we extend the Duman-King idea of approximation of functions by positive linear operators preserving , . Using a modification of certain operators preserving and , we introduce operators which preserve and and next we define operators for -times differentiable functions. We show that and have better approximation properties than and .