%0 Journal Article
%T Polynomial of best uniform approximation to $x^{-1}$ and smoothing in two-level methods
%A Johannes K. Kraus
%A Panayot S. Vassilevski
%A Ludmil T. Zikatanov
%J Mathematics
%D 2010
%I arXiv
%X We derive a three-term recurrence relation for computing the polynomial of best approximation in the uniform norm to $x^{-1}$ on a finite interval with positive endpoints. As application, we consider two-level methods for scalar elliptic partial differential equation (PDE), where the relaxation on the fine grid uses the aforementioned polynomial of best approximation. Based on a new smoothing property of this polynomial smoother that we prove, combined with a proper choice of the coarse space, we obtain as a corollary, that the convergence rate of the resulting two-level method is uniform with respect to the mesh parameters, coarsening ratio and PDE coefficient variation.
%U http://arxiv.org/abs/1002.1859v3