Factored approximate inverse preconditioners with dynamic sparsity patterns

We propose two sparsity pattern selection algorithms for factored approximate inverse preconditioners to solve general sparse matrices. The sparsity pattern is adaptively updated in the construction phase by using combined information of the inverse and original triangular factors of the original matrix. In order to determine the sparsity pattern, our first algorithm uses the norm of the inverse factors multiplied by the largest absolute value of the original factors, and the second employs the norm of the inverse factors divided by the norm of the original factors. Experimental results show that these algorithms improve the robustness of the preconditioners to solve general sparse matrices.