Taylor and Francis Ltd.;Abingdon: Taylor & Francis
摘要:
摘要： We show that a bounded linear operator is a multiple of a unitary operator if and only if and always have the same numerical radius or the same numerical range for all (rank one) . More generally, for any bounded linear operators , we show that and always have the same numerical radius (resp., the same numerical range) for all (rank one) if and only if (resp., ) is a multiple of a unitary operator for some . We extend the result to other types of generalized numerical ranges including the -numerical range and the higher rank numerical range. 出版者： Abingdon: Taylor & Francis 出版日期： 2016-01-02 出處： Linear & multilinear algebra, 2016-01, Vol.64 (1), p.58-67 版權： 2015 Taylor & Francis 2015 版權： 2015 Taylor & Francis 識別號： ISSN: 0308-1087 識別號： EISSN: 1563-5139 識別號： DOI: 10.1080/03081087.2015.1024195
