Taylor and Francis Ltd.;Abingdon: Taylor & Francis
摘要:
摘要： An n-by-n ( ) weighted shift matrix A is one of the form where the 's, called the weights of A, are complex numbers. Let denote the -by- principal submatrix of A obtained by deleting its jth row and jth column. We show that the boundary of numerical range W(A) has a line segment if and only if the 's are nonzero and for some . This refines previous results of Tsai and Wu on numerical ranges of weighted shift matrices. In addition, we give an example showing that there is a weighted shift matrix with line segments on the boundary of its numerical range such that the moduli of its weights are not periodic. 出版者： Abingdon: Taylor & Francis 出版日期： 2014-05-04 出處： Linear & multilinear algebra, 2014-05, Vol.62 (5), p.568-578 版權： 2013 Taylor & Francis 2013 版權： 2013 Taylor & Francis 識別號： ISSN: 0308-1087 識別號： EISSN: 1563-5139 識別號： DOI: 10.1080/03081087.2013.804522
