High Order Approximation with Multivariate Generalized Gauss–Weierstrass Singular Integrals

This research and survey chapter deals exclusively with the study of the approximation of generalized multivariate Gauss–Weierstrass singular integrals to the identity-unit operator. Here we study quantitatively most of their approximation properties. The multivariate generalized Gauss–Weierstrass operators are not in general positive linear operators