NUMERICAL RANGE AND POSITIVE BLOCK MATRICES
| Affiliation auteurs | Affiliation ok |
| Titre | NUMERICAL RANGE AND POSITIVE BLOCK MATRICES |
| Type de publication | Journal Article |
| Year of Publication | 2021 |
| Auteurs | Bourin J-C, Lee E-Y |
| Journal | BULLETIN OF THE AUSTRALIAN MATHEMATICAL SOCIETY |
| Volume | 103 |
| Pagination | PII S0004972720000520 |
| Date Published | FEB |
| Type of Article | Article |
| ISSN | 0004-9727 |
| Mots-clés | norm inequalities, Numerical range, Partitioned matrices |
| Résumé | We obtain several norm and eigenvalue inequalities for positive matrices partitioned into four blocks. The results involve the numerical range W(X) of the off-diagonal block X, especially the distance d from 0 to W(X). A special consequence is an estimate, diamW([(A)(X*) (X)(B)]) - diamW(A + B/2) >= 2d, between the diameters of the numerical ranges for the full matrix and its partial trace. |
| DOI | 10.1017/S0004972720000520 |