# Upper and lower bounds for numerical radii of block shifts

Hwa Long Gau, Pei Yuan Wu

1 引文 斯高帕斯（Scopus）

## 摘要

For an n-by-n complex matrix A in a block form with the (possibly) nonzero blocks only on the diagonal above the main one, we consider two other matrices whose nonzero entries are along the diagonal above the main one and consist of the norms or minimum moduli of the diagonal blocks of A. In this paper, we obtain two inequalities relating the numeical radii of these matrices and also determine when either of them becomes an equality.

原文 ???core.languages.en_GB??? 15-27 13 Bulletin of the Iranian Mathematical Society 41 7 已出版 - 12月 2015