Exponential moments and simultaneous approximation properties for Durrmeyer type operators with weights of Szász basis functions

Abstract

The present paper deals with the approximation properties for exponential functions of general Durrmeyer type operators having the weights of Sz\'asz basis functions. Here we give explicit expressions for exponential type moments by means of which we establish, for the derivatives of the operators, the Voronovskaja formulas for functions of exponential growth and the corresponding weighted quantitative estimates for the remainder in simultaneous approximation.