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The spectra of preconditioned Toeplitz matrix sequences can have gaps

  • University of Insubria

Research output: Contribution to journalArticlepeer-review

Abstract

Different than for the case of Toeplitz matrix sequences {T n(f)}, f ∈ L1, we can prove that the closure of the union of all the spectra of preconditioned matrix sequences of the form {T n-1 (g)Tn(f)}, f, g ∈ L1, g ≥ 0, can have gaps if the essential range of f/g is not connected. The result has important consequences on the practical use of band Toeplitz precouditioners widely used in the literature both for (multilevel) ill-conditioned positive definite and (multilevel) indefinite Toeplitz linear systems.

Original languageEnglish
Pages (from-to)930-946
Number of pages17
JournalSIAM Journal on Matrix Analysis and Applications
Volume25
Issue number4
DOIs
StatePublished - 2004

Keywords

  • Generating function
  • Preconditioning
  • Spectral distribution and localization results
  • Toeplitz matrix

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