New band Toeplitz preconditioners for ill-conditioned symmetric positive definite Toeplitz systems

dc.contributor.authorNoutsos, D.en
dc.contributor.authorVassalos, P.en
dc.date.accessioned2015-11-24T17:25:44Z
dc.date.available2015-11-24T17:25:44Z
dc.identifier.issn0895-4798-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/13089
dc.rightsDefault Licence-
dc.subjectlow rank correctionen
dc.subjecttoeplitz matrixen
dc.subjectconjugate gradienten
dc.subjectrational interpolation and approximationen
dc.subjectpreconditioneren
dc.subjectmatricesen
dc.titleNew band Toeplitz preconditioners for ill-conditioned symmetric positive definite Toeplitz systemsen
heal.abstractIt is well known that preconditioned conjugate gradient (PCG) methods are widely used to solve ill-conditioned Toeplitz linear systems T-n(f)x = b. In this paper we present a new preconditioning technique for the solution of symmetric Toeplitz systems generated by nonnegative functions f with zeros of even order. More specifically, f is divided by the appropriate trigonometric polynomial g of the smallest degree, with zeros the zeros of f, to eliminate its zeros. Using rational approximation we approximate rootf/g by p/q, p, q trigonometric polynomials and consider p(2)g/q(2) as a very satisfactory approximation of f. We propose the matrix M-n = B-n(-1)(q)B-n(p(2)g)B-n(-1)(q), where B (.) denotes the associated band Toeplitz matrix, as a preconditioner whence a good clustering of the spectrum of its preconditioned matrix is obtained. We also show that the proposed technique can be very flexible, a fact that is confirmed by various numerical experiments so that in many cases it constitutes a much more efficient strategy than the existing ones.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.secondary<Go to ISI>://000174378500009-
heal.journalNameSiam Journal on Matrix Analysis and Applicationsen
heal.journalTypepeer reviewed-
heal.languageen-
heal.publicationDate2002-
heal.publisherSociety for Industrial and Applied Mathematicsen
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μαθηματικώνel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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