On the perturbation theory for unitary eigenvalue problems

Authors
Bohnhorst, B Bunse-Gerstner, A Fassbender, H
Citation
B. Bohnhorst et al., On the perturbation theory for unitary eigenvalue problems, SIAM J MATR, 21(3), 2000, pp. 809-824
Citations number
34
Categorie Soggetti
Mathematics
Journal title
SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
ISSN journal
08954798 → ACNP
Volume
21
Issue
3
Year of publication
2000
Pages
809 - 824
Database
ISI
SICI code
0895-4798(20000309)21:3<809:OTPTFU>2.0.ZU;2-E
Abstract
Some aspects of the perturbation theory for eigenvalues of unitary matrices are considered. Making use of the close relation between unitary and Hermi tian eigenvalue problems a Courant-Fischer-type theorem for unitary matrice s is derived and an inclusion theorem analogous to the Kahan theorem for He rmitian matrices is presented. Implications for the special case of unitary Hessenberg matrices are discussed.