A comparison of two effective methods for reordering columns within supernodes

Abstract: In some papers, researchers have found two very good methods for reordering columns within supernodes in sparse Cholesky factors; these reorderings can be very useful for certain factorization methods. The first of these reordering methods is based on modeling the underlying problem as a traveling salesman problem (TSP), and the second of these methods is based on partition refinement (PR). In this paper, we devise a fair way to compare the two methods. While the two methods are virtually the same in the quality of the reorderings that they produce, PR should be the method of choice because PR reorderings can be computed using far less time and storage than TSP reorderings.