Local and Global Approximation Theorems for Positive Linear Operators Original Research Article

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.