Zobrazeno 1 - 10
of 53
pro vyhledávání: '"John Maroulas"'
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
Opuscula Mathematica, Vol 33, Iss 2, Pp 307-321 (2013)
In this paper we consider Rellich's diagonalization theorem for analytic self-adjoint operator functions and investigate variational principles for their eigenfunctions and interlacing statements. As an application, we present a characterization for
Externí odkaz:
https://doaj.org/article/b2b85cfcb4434f90a7583c9714718bec
Autor:
Aikaterini Aretaki, John Maroulas
Publikováno v:
Opuscula Mathematica, Vol 31, Iss 3, Pp 303-315 (2011)
A presentation of numerical ranges for rectangular matrices is undertaken in this paper, introducing two different definitions and elaborating basic properties. Further, we extend to the \(q\)-numerical range.
Externí odkaz:
https://doaj.org/article/6e0f16ea558f406092b2c204c0c25441
Autor:
John Maroulas
Publikováno v:
Linear Algebra and its Applications. 506:226-243
The analysis of any Hessenberg matrix as a product of a companion matrix and a triangular matrix is presented in this paper. The factors are explicitly given on terms of the entries of the Hessenberg matrix and, further, various factorizations are un
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::6481d4cd36044df6f97246a747596593
https://doi.org/10.1016/j.laa.2016.05.026
https://doi.org/10.1016/j.laa.2016.05.026
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
The Electronic Journal of Linear Algebra. 31:244-262
A pair of matrices is said to be imbeddable precisely when one is an isometric projection of the other on a suitable subspace. The concept of imbedding has been the subject of extensive study. Particular emphasis has been placed on relating the spect
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::77511eb513634a1ab44acfdcff8f96c5
https://doi.org/10.13001/1081-3810.2832
https://doi.org/10.13001/1081-3810.2832
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
SIAM Journal on Matrix Analysis and Applications. 37:1022-1037
For an $n \times n$ matrix $A$ and an integer $k \in [1,n]$, the concept of the higher rank numerical range $\Lambda_k(A)=\left\{z \in \mathbb{C}:V^*AV=zI_k, \; V \in \mathbb{C}^{n \times k}, \; V^*V=I_k\right\}$ has been introduced in relation to th
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::7bd5dc8c9b180c0f2e470dda4cd3ab32
https://doi.org/10.1137/15m1009342
https://doi.org/10.1137/15m1009342
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
Applied Mathematics and Computation. 233:557-564
For several applications, it is highly desirable to understand how the eigenvalues of an imbeddable matrix V ∗ AV , where V ∈ C n × k is an isometry, are distributed throughout the numerical range of A ∈ C n × n . There has been extensive stu
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::f10c72fbc490a89533f45941f2ddd6c6
https://doi.org/10.1016/j.amc.2014.02.016
https://doi.org/10.1016/j.amc.2014.02.016
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
Linear Algebra and its Applications. 439:552-564
Let w(A) be the numerical range of a matrix A ∈ C n × n and a set of points μ 1 , … , μ n - k ∈ w ( A ) that define the spectrum σ ( B ) of a matrix B ∈ C ( n - k ) × ( n - k ) . The problem of imbedding concerns the existence and constr
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::21f22547b5b7331e51ee016e96cbd28c
https://doi.org/10.1016/j.laa.2013.03.013
https://doi.org/10.1016/j.laa.2013.03.013
Autor:
Georgios Katsouleas, John Maroulas
Publikováno v:
Applied Mathematics and Computation. 219:7048-7055
Let a normal matrix [email protected]?C^n^x^n and @m"1 a given point in its numerical range w(A) that is not an eigenvalue. In this paper, we study the problem of construction of an isometry [email protected]?C^n^x^(^n^-^k^) (1=
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::369a074cfcf36767063da93b8fd413d0
https://doi.org/10.1016/j.amc.2012.12.071
https://doi.org/10.1016/j.amc.2012.12.071
Autor:
John Maroulas, Maria Adam
Publikováno v:
Communications in Statistics - Theory and Methods. 35:2263-2273
In this article, a useful proposition relating the canonical correlations in multi-way layout to the singular values of a specific matrix is proved and also a geometrical explanation of canonical correlations as an angle between subspaces is given.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::02594d699812910e084596cd374d287f
https://doi.org/10.1080/03610920600853522
https://doi.org/10.1080/03610920600853522
Autor:
John Maroulas, Maria Adam
Publikováno v:
Linear Algebra and its Applications. 341(1-3):403-418
Let A be a normal matrix and consider the polygon NR[A]={x * Ax: ∥x∥=1}. If υ * Aυ∈ int NR[A] , a projector matrix P υ is defined such that NR [ P * υ AP υ ] is supported by all or some edges of a polygon.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8b629b1d7c8860e37b29a927ab1ae5fa