A Sparse-Sparse Iteration for Computing a Sparse Incomplete   Factorization of the Inverse of an SPD Matrix
  In this paper, a method via sparse-sparse iteration for computing a sparse incomplete factorization of the inverse of a symmetric positive definite matrix is proposed. The resulting factorized sparse approximate inverse is used as a preconditioner for solving symmetric positive definite linear systems of equations by using the preconditioned conjugate gradient algorithm. Some numerical experiments on test matrices from the Harwell-Boeing collection for comparing the numerical performance of the presented method with one available well-known algorithm are also given. 
Davod Khojasteh Salkuyeh and Faezeh Toutounian