Quadratic convergence of approximations by CCC-Schoenberg operators

Abstract

We generalize to the Canonical Complete Chebyshev splines some properties already known for Extended Chebyshev and piecewise Extended Chebyshev splines, like Marsden identity and Greville points. Also, we represent an interesting algorithm which leads to numerically stable expressions for the Greville points for CCC-splines. We show that any CCC-spline space provides us with infinite number of operators of the Schoenberg-type, and we give a simple characterization of them. After proving few important properties, we establish a sufficient condition for quadratic convergence of approximations by CCC-Schoenberg operators to a given function.