On the two-level preconditioning in least squares method (Փոքրագույն քառակուսիների եղանակում երկմակարդակային վերապայմանավորման մասին)

Abstract

In this paper we have discussed an idea of constructing algebraic two-level preconditioners for NS-matrices arising in data fitting by least squares method using piecewise linear basis functions. The results obtained can be useful for constructing multilevel preconditioners. They also serve as a basis when considering more smooth approximating functions. We will study these issues in subsequent publications.