Analytical bounds for block approximate factorization methods
نویسندگان
چکیده
منابع مشابه
Ordering Methods for Approximate Factorization Preconditioning
We investigate the ordering and ll-in strategies for approximate factorization preconditioning, focusing on automatic procedures to take care that a user friendly solver should converge equally fast whatever the original numbering of the unknowns. Considering the discrete PDE context, we pay particular attention to anisotropic problems for which factorizations without ll-in may behave poorly, w...
متن کاملOn Approximate Factorization Methods for Block Matrices Suitable for Vector and Parallel Processors
Some existence results for methods based on the approximate factorization of block matrices are proven. These methods are based on recursive computations of diagonal block matrices and the approximation of their inverses to preserve sparsity. We also discuss a recently proposed [l] inverse free factorization method and present some numerical tests for it.
متن کاملSome Preconditioners for Block Pentadiagonal Linear Systems Based on New Approximate Factorization Methods
In this paper, getting an high-efficiency parallel algorithm to solve sparse block pentadiagonal linear systems suitable for vectors and parallel processors, stair matrices are used to construct some parallel polynomial approximate inverse preconditioners. These preconditioners are appropriate when the desired target is to maximize parallelism. Moreover, some theoretical results about these pre...
متن کاملStability of Approximate Factorization with theta-Methods
Approximate factorization seems for certain problems a viable alternative to time splitting. Since a splitting error is avoided, accuracy will in general be favourable compared to time splitting methods. However, it is not clear to what extent stability is a ected by factorization. Therefore we study here the e ects of factorization on a simple, low order method, namely the -method. For this si...
متن کاملLower Bounds for the Approximate Degree of Block-Composed Functions
We describe a new hardness amplification result for point-wise approximation of Boolean functions by low-degree polynomials. Specifically, for any function f on N bits, define F(x1, . . . ,xM) = OMB( f (x1), . . . , f (xM)) to be the function on M ·N bits obtained by block-composing f with a specific DNF known as ODD-MAX-BIT. We show that, if f requires large degree to approximate to error 2/3 ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Linear Algebra and its Applications
سال: 1993
ISSN: 0024-3795
DOI: 10.1016/0024-3795(93)90320-n