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A method for separating nearly multiple eigenvalues for Hermitian matrix. (English) Zbl 1112.65032

The following problem is discussed: Given a symmetric matrix and assume that by one of the methods of verified computation a small interval has been determined which encloses \(k\) of its eigenvalues. Verify that they are not a k-fold eigenvalue. An algorithm using verified computation, e.g. using INTLAB, is given, which can decide this question. Two examples with \(k=2\) (the infamous Wilkinson matrix) and \(k=3\) illustrate the method.

MSC:

65F15 Numerical computation of eigenvalues and eigenvectors of matrices
65G20 Algorithms with automatic result verification
15A42 Inequalities involving eigenvalues and eigenvectors

Software:

INTLAB
Full Text: DOI

References:

[1] Rump, S. M., INTLAB-INTerval LABoratory, (Cesndes, Tibor, Developments in Reliable Computing (1999), Kluwer Academic Publishers: Kluwer Academic Publishers The Netherlands), 77-104 · Zbl 0949.65046
[2] Rump, S. M., Computational error bounds for multiple or nearly multiple eigenvalues, Linear Algebra Appl., 324, 209-226 (2001) · Zbl 0986.65031
[3] Wilkinson, J. H., The Algebric Eigenvalue Problem (1965), Oxford University Press: Oxford University Press London · Zbl 0258.65037
[4] Yamamoto, N., A simple method for error bounds of eigenvalues of symmetric matrices, Linear Algebra Appl., 324, 227-234 (2001) · Zbl 0981.65042
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