Numerical range and positive block 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, diam W A X X * B − diam W A + B 2 ≥ 2d, between the diameters of the numerical ranges for the full matrix and its partial trace.
Domaines
Analyse fonctionnelle [math.FA]Origine | Fichiers produits par l'(les) auteur(s) |
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