The Boundary of Numerical Ranges

碩士 === 東吳大學 === 數學系 === 100 === In this paper we study the boundary of the numerical ranges. Let S = {x : x^*x = 1, x E C^n}. The numerical range of an n × n complex matrix A is defined to be the set W(A) = {x^*Ax : x 2 S}. We list some fundamental properties in section 1. In section 2, we discuss t...

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Bibliographic Details
Main Authors: Wen-chih Liu, 劉文智
Other Authors: Mao-Ting Chien
Format: Others
Language:en_US
Published: 2012
Online Access:http://ndltd.ncl.edu.tw/handle/41186791618919990845
Description
Summary:碩士 === 東吳大學 === 數學系 === 100 === In this paper we study the boundary of the numerical ranges. Let S = {x : x^*x = 1, x E C^n}. The numerical range of an n × n complex matrix A is defined to be the set W(A) = {x^*Ax : x 2 S}. We list some fundamental properties in section 1. In section 2, we discuss the angle between x Ay and y Ax when x Ax lies on the boundary of W(A). In section 3, we study properties of corner x^*Ax of W(A). Finally we give some special geometry in section 4. i