Advances in Numerical Analysis
Volume 2011 (2011), Article ID 703435, 9 pages
Research Article

Different Versions of ILU and IUL Factorizations Obtained from Forward and Backward Factored Approximate Inverse Processes—Part I

Department of Applied Mathematics, Sabzevar Tarbiat Moallem University, Sabzevar, Iran

Received 29 August 2011; Accepted 6 October 2011

Academic Editor: Raytcho Lazarov

Copyright © 2011 Amin Rafiei and Fatemeh Shahlaei. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present an incomplete UL (IUL) decomposition of matrix 𝐴 which is extracted as a by-product of BFAPINV (backward factored approximate inverse) process. We term this IUL factorization as IULBF. We have used ILUFF [3] and IULBF as left preconditioner for linear systems. Different versions of ILUFF and IULBF preconditioners are computed by using different dropping techniques. In this paper, we compare quality of different versions of ILUFF and IULBF preconditioners.