Betterment for estimates of the numerical radii of Hilbert space operators
نویسندگان
1 Department of Mathematics, Payame Noor University (PNU), P.O. Box, 19395-4697, Tehran, Iran
2 Department of Mathematics, Ferdows Branch, Islamic Azad University, Ferdows, Iran
doi
10.22060/ajmc.2022.21907.1122چکیده
We give several inequalities involving numerical radii $\omega \left( \cdot \right)$ and the usual operator norm $\|\cdot\|$ of Hilbert space operators. These inequalities lead to a considerable improvement in the well-known inequalities\begin{equation*}\frac{1}{2}\left\| T \right\|\le \omega \left( T \right)\le \left\| T \right\|.\end{equation*}
