Triangularizing matrices by congruence

Congruence of Hermitian Matrices by Hermitian Matrices

Two Hermitian matrices A, B ∈ Mn(C) are said to be Hermitian-congruent if there exists a nonsingular Hermitian matrix C ∈ Mn(C) such that B = CAC. In this paper, we give necessary and sufficient conditions for two nonsingular simultaneously unitarily diagonalizable Hermitian matrices A and B to be Hermitian-congruent. Moreover, when A and B are Hermitian-congruent, we describe the possible iner...

A Fast+practical+deterministic Algorithm for Triangularizing Integer Matrices

This paper presents a new algorithm for computing the row reduced echelon form triangularization H of an n m integer input matrix A. The cost of the algorithm is O(nmr 2 log 2 rjjAjj + r 4 log 3 rjjAjj) bit operations where r is the rank of A and jjAjj = max ij jA ij j. This complexity result assumes standard (quadratic) integer arithmetic but still matches, in the paramaters n, m and r, the be...

Fleck’s binomial congruence using circulant matrices

Assessing Congruence Among Ultrametric Distance Matrices

Recently, a test of congruence among distance matrices (CADM) has been developed. The null hypothesis is the incongruence among all data matrices. It has been shown that CADM has a correct type I error rate and good power when applied to independently-generated distance matrices. In this study, we investigate the suitability of CADM to compare ultrametric distance matrices. We tested the type I...

Triangularizing Quadratic Matrix Polynomials

We show that any regular quadratic matrix polynomial can be reduced to an upper triangular quadratic matrix polynomial over the complex numbers preserving the finite and infinite elementary divisors. We characterize the real quadratic matrix polynomials that are triangularizable over the real numbers and show that those that are not triangularizable are quasi-triangularizable with diagonal bloc...