Numerical experiments are presented whereby the effect of reorderings on th
e convergence of preconditioned Krylov subspace methods for the solution of
nonsymmetric linear systems is shown. The preconditioners used in this stu
dy are different variants of incomplete factorizations. It is shown that ce
rtain reorderings for direct methods, such as reverse Cuthill-McKee, can be
very beneficial. The benefit can be seen in the reduction of the number of
iterations and also in measuring the deviation of the preconditioned opera
tor from the identity.