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On the optimality and sharpness of Laguerre's lower bound on the smallest eigenvalue of a symmetric positive definite matrix

Yusaku Yamamoto (2017)

Applications of Mathematics

Lower bounds on the smallest eigenvalue of a symmetric positive definite matrix A m × m play an important role in condition number estimation and in iterative methods for singular value computation. In particular, the bounds based on Tr ( A - 1 ) and Tr ( A - 2 ) have attracted attention recently, because they can be computed in O ( m ) operations when A is tridiagonal. In this paper, we focus on these bounds and investigate their properties in detail. First, we consider the problem of finding the optimal bound that can be computed...

On the separation of eigenvalues by the permutation group

Grega Cigler, Marjan Jerman (2014)

Special Matrices

Let A be an invertible 3 × 3 complex matrix. It is shown that there is a 3 × 3 permutation matrix P such that the product PA has at least two distinct eigenvalues. The nilpotent complex n × n matrices A for which the products PA with all symmetric matrices P have a single spectrum are determined. It is shown that for a n × n complex matrix [...] there exists a permutation matrix P such that the product PA has at least two distinct eigenvalues.

On the signless Laplacian spectral characterization of the line graphs of T -shape trees

Guoping Wang, Guangquan Guo, Li Min (2014)

Czechoslovak Mathematical Journal

A graph is determined by its signless Laplacian spectrum if no other non-isomorphic graph has the same signless Laplacian spectrum (simply G is D Q S ). Let T ( a , b , c ) denote the T -shape tree obtained by identifying the end vertices of three paths P a + 2 , P b + 2 and P c + 2 . We prove that its all line graphs ( T ( a , b , c ) ) except ( T ( t , t , 2 t + 1 ) ) ( t 1 ) are D Q S , and determine the graphs which have the same signless Laplacian spectrum as ( T ( t , t , 2 t + 1 ) ) . Let μ 1 ( G ) be the maximum signless Laplacian eigenvalue of the graph G . We give the limit of μ 1 ( ( T ( a , b , c ) ) ) , too.

On the vectors associated with the roots of max-plus characteristic polynomials

Yuki Nishida, Sennosuke Watanabe, Yoshihide Watanabe (2020)

Applications of Mathematics

We discuss the eigenvalue problem in the max-plus algebra. For a max-plus square matrix, the roots of its characteristic polynomial are not its eigenvalues. In this paper, we give the notion of algebraic eigenvectors associated with the roots of characteristic polynomials. Algebraic eigenvectors are the analogues of the usual eigenvectors in the following three senses: (1) An algebraic eigenvector satisfies an equation similar to the equation A x = λ x for usual eigenvectors. Under a suitable assumption,...

On the weak robustness of fuzzy matrices

Ján Plavka (2013)

Kybernetika

A matrix A in ( max , min ) -algebra (fuzzy matrix) is called weakly robust if A k x is an eigenvector of A only if x is an eigenvector of A . The weak robustness of fuzzy matrices are studied and its properties are proved. A characterization of the weak robustness of fuzzy matrices is presented and an O ( n 2 ) algorithm for checking the weak robustness is described.

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