Graph perturbations
The authors are concerned with the construction of a new class of preconditioners for Stieltjes matrices by modified incomplete LU factorizations based on consistent orderings of the unknowns. Since the standard diagonal perturbation techniques may result in bad spectral condition numbers, a new perturbation technique, dubbed ``graph perturbation'', is suggested which is based on the use of some additional nonzero entries in appropriately prespecified positions. Lower and upper bounds for the spectrum of the preconditioned matrix are derived and the theoretical findings are supported by some numerical results.
scientific article; zbMATH DE number 721006
scientific article