Results 11 to 20 of about 53 (52)
Some inequalities for unitarily invariant norms of matrices [PDF]
, 2011 This article aims to discuss inequalities involving unitarily invariant norms. We obtain a refinement of the inequality shown by Zhan. Meanwhile, we give an improvement of the inequality presented by Bhatia and Kittaneh for the Hilbert-Schmidt norm.
Youyi Jiang, Limin Zou, Shaoheng Wang
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On the shape of numerical range of matrix polynomials [PDF]
, 2001 The numerical range of an n×n matrix polynomial P(λ)=Amλm+⋯+A1λ+A0 is defined byW(P)=λ∈C:x*P(λ)x=0,x∈Cn,x≠0.In this paper, we investigate the shape of W(P) by using the notion of local dimension.
Psarrakos, P +5 more
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Fejér–Riesz factorization in the QRC-subalgebra and circularity of the quaternionic numerical range [PDF]
Journal Article, Faculty of Natural and Agricultural Sciences, Pure and Applied Analytics -- Potchefstroom CampusWe provide a characterization when the quaternionic numerical range of a matrix is a closed ball with center 0.
Van Straaten, Madelein +2 more
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The c-numerical range of a quaternion skew-Hermitian matrix is convex [PDF]
Journal Article, Faculty of Natural and Agricultural Sciences, Pure and Applied Analytics-- Potchefstroom CampusWe show that the c-numerical range of a non-scalar skew-Hermitian quaternion matrix is convex.
Thiersen, Madelein +2 more
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Linear preservers of Tensor product of Unitary Orbits
, 2020 It is shown that the linear group of automorphism of Hermitian matrices which preserves the tensor product of unitary orbits is generated by natural automorphisms: change of an orthonormal basis in each tensor factor, partial transpose in each tensor ...
Chi-Kwong Li +5 more
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Preservers of unitary similarity functions on Lie products of matrices
, 2020 In memory of Professor Hans Schneider MSC: 15A60 46B04 Keywords: Lie product Unitary similarity invariant function Pseudo spectrum Denote by M n the set of n ×n complex matrices. Let f : M n → [0, ∞) be a continuous map such that f (μU AU * ) = f (A) for
Chi-Kwong Li +2 more
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Isometries Between Matrix Algebras
, 2007 As an attempt to understand linear isometries between C # -algebras without the surjectivity assumption, we study linear isometries between matrix algebras. Denote by Mm the algebra of mm complex matrices. If k n and # : M n k has the form
Chi-kwong Li +3 more
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Interpolation $H^{\infty}$ et théorèmes de plongements pour des fonctions rationnelles
, 2019 International audienceWe consider a Nevanlinna-Pick interpolation problem on finite sequences of the unit disc D constrained by Hardy and radial-weighted Bergman norms. We find sharp asymptotics on the corresponding interpolation constants.
Baranov, Anton, Zarouf, Rachid
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If A Matrix Has Only A Single Eigenvalue How Sensitive Is This Eigenvalue?
, 1997 . For matrices with a single eigenvalue we analyse the sensitivity of the eigenvalue to perturbations in the matrix. We derive a closed form result that is similar in spirit to an analytical result by Lidskii; improve a bound by Henrici; and express the ...
Grace E. Cho, Ilse C.F. Ipsen
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HIGHER-RANK NUMERICAL RANGES AND DILATIONS
, 2008 . For any n-by-n complex matrix A and any k, 1 ≤ k ≤ n, let Λ k(A) = {λ ∈ C: X ∗ AX = λI k for some n-by-k X satisfying X ∗ X = I k} be its rank-k numerical range.
Hwa-long Gau, Chi-kwong Li, Pei Yuan Wu
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