Numerical radius of certain two-by-two block matrices

Hwa-Long Gau, Jia-Huo Hong, Chi-Kwong Li +1

We investigate the numerical range $W(T)$ and numerical radius $w(T)$ of operators of the form $T=\left(\begin{array}{cc}A& B\\ 0& 0\end{array}\right)$. We show that $W(T)$ is the union…