Document Type : Research Paper
Hakim Sabzevari University
In this paper, an efficient dropping criterion has been used to compute the IUL factorization obtained from Backward Factored APproximate INVerse (BFAPINV) and ILU factorization obtained from Forward Factored APproximate INVerse (FFAPINV) algorithms. We use different drop tolerance parameters to compute the preconditioners. To study the effect of such a dropping on the quality of the ILU and IUL factorizations, we have used the preconditioners as the right preconditioners for several linear systems and then, the Krylov subspace methods have been used to solve the preconditioned systems. To avoid storing matrix $A$ in two CSR and CSC formats, the linked lists trick has been used in the implementations. As the preprocessing, the multilevel nested dissection reordering has also been used.