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Lower bounds for the spread of a matrix. (English) Zbl 0578.15013

This paper refers to some lower bounds for the spread \(s(A)=\max_{i,j}| \lambda_ i-\lambda_ j|\) of an \(n\times n\) matrix \(A=(a_{ij})\), \(\lambda_ i\) being its eigenvalues. They proceed from the following results due to L. Mirsky [Duke Math. J. 24, 591- 599 (1957; Zbl 0081.251)]: s(A)\(\geq \sqrt{3} \sup (u,Av)\) for A normal and \(s(A)=2 \sup (u,Av)\) for A Hermitian; sup is taken with respect to all orthonormal vectors u,v. By appropriate choices of u and v one derives four results. For instance s(A)\(\geq | \sum_{i\neq j}a_{ij} | /(n-1)\) and, A being symmetric, s(A)\(\geq 2\nu\), where \(\nu\) denotes the standard deviation of the row sums of A. Comparisons of the bounds derived, with several known bounds, are made in the final part of the paper.
Reviewer: M.Voicu

MSC:

15A42 Inequalities involving eigenvalues and eigenvectors
15B57 Hermitian, skew-Hermitian, and related matrices

Citations:

Zbl 0081.251
Full Text: DOI

References:

[1] Brauer, A.; Mewborn, A. C., The greatest distance between two characteristic roots of a matrix, Duke Math. J., 26, 653-661 (1959) · Zbl 0095.01202
[2] R. Grone, C. R. Johnson, E. Marques de Sa, and H. Wolkowicz, Constrained ranges of sesquilinear forms, manuscript.; R. Grone, C. R. Johnson, E. Marques de Sa, and H. Wolkowicz, Constrained ranges of sesquilinear forms, manuscript.
[3] Johnson, C. R., Normality and the numerical range, Linear Algebra Appl., 15, 89-94 (1976) · Zbl 0337.15019
[4] Merikoski, J. K., On a lower bound for the Perron eigenvalue, BIT, 19, 39-42 (1979) · Zbl 0398.65016
[5] Minc, H.; Marcus, M., A Survey of Matrix Theory and Matrix Inequalities (1964), Prindle, Weber and Schmidt · Zbl 0126.02404
[6] Mirsky, L., Inequalities for normal and Hermitian matrices, Duke Math. J., 24, 591-599 (1957) · Zbl 0081.25101
[7] Mirsky, L., The spread of a matrix, Mathematics, 3, 127-130 (1956) · Zbl 0073.00903
[8] Parker, W. V., The characteristics roots of matrices, Duke Math. J., 12, 519-526 (1945) · Zbl 0060.03605
[9] Wolkowicz, H.; Styan, G. P.H., Bounds for eigenvalues using traces, Linear Algebra Appl., 29, 471-506 (1980) · Zbl 0435.15015
[10] Wolkowicz, H.; Styan, G. P.H., More bounds for eigenvalues using traces, Linear Algebra Appl., 31, 1-17 (1980) · Zbl 0434.15003
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