可分解友矩陣之研究;A Study on Reducible Companion Matrices

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/63709

Title:	可分解友矩陣之研究;A Study on Reducible Companion Matrices
Authors:	孫梅珊;Sun,Mei-San
Contributors:	數學研究所
Keywords:	可分解之友矩陣;numerical range;reducible companion matrices
Date:	2006-06-29
Issue Date:	2014-05-08 15:26:34 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文探討「可分解友矩陣」的一些性質。我們證明若一個非么正友矩陣 A 可分解成A1 ⊕ A2，則且。令1 1 rank( ) 1 kI −AA = = 2 2 rank( ) 1 n k I AA − − { : rank( * )=1 and \| \| , ( )} n n Sα ≡ A∈M I−AA λ =α ∀λ ∈σ A ，則相當於1 是屬於A k Sα 且2 是屬於A 1/ n k S α − 。亦證明每一個屬於n Sα 集合內的矩陣均具有循環、不可分解、且其數值域之邊界為一可微曲線。並證明下列敘述互為等價：(a) ；(b) ；(c) 1 W(A)=W(A) 1 1) n 2 n1 W(J ) W(A − ⊆ W(A ) W(J ) − ⊆ 。 ;In this thesis, we study some properties of reducible companion matrices. We first prove that if a nonunitary reducible companion matrix A is unitarily equivalent to the direct sum A_1oplus A_2 on mathbb{C}^koplusmathbb{C}^{n-k} with sigma(A_1)={aom_n^{j_1},cdots,aom_n^{j_k}} and sigma(A_2)={(1/ ar{a})om_n^{j_{k+1}},cdots,(1/ ar{a})om_n^{j_n}},where \|a\|>1 and om_n denotes the nth primitive root of 1,then rank(I_k-A^{}_1A_1)=rank(I_{n-k}-A^{}_2A_2)=1. We denote mathcal{S}^{al}_nequiv{Ain M_n:rank(I_n-A^{*}A)=1 and \|la\|=al,forall: lainsigma(A)}, thus A_1 is in mathcal{S}^{al}_k and A_2 is in mathcal{S}^{1/al}_{n-k}. Next, we prove that every mathcal{S}^{al}_n-matrix is irreducible, cyclic, and the boundary of its numerical range is a differentiable curve. Furthermore, we show that the following statements are equivalent: (a) W(A)=W(A_1); (b)W(J_{n-1})subseteq W(A_1); (c)W(A_2)subseteq W(J_{n-1}).
Appears in Collections:	[Graduate Institute of Mathematics] Electronic Thesis & Dissertation

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