A note on norm estimates of the numerical radius
Sano, Takashi
Proc. Japan Acad. Ser. A Math. Sci., Tome 84 (2008) no. 1, p. 5-7 / Harvested from Project Euclid
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For a bounded linear operator $A$ on a Hilbert space $\mathcal{H}$, let $\| A \|$ denote the operator norm and $w(A)$ the numerical radius. It is well-known that \begin{equation*} \frac{1}{2} \| A \| ≤q w(A) ≤q \| A \|. \end{equation*} For equalities, we consider linear operators $A$ with $A^{2} = 0$ and normaloid matrices.
Publié le : 2008-01-15
Classification:  Numerical radius,  normaloid matrix,  15A60,  47A12 
@article{1201186677,
     author = {Sano, Takashi},
     title = {A note on norm estimates of the numerical radius},
     journal = {Proc. Japan Acad. Ser. A Math. Sci.},
     volume = {84},
     number = {1},
     year = {2008},
     pages = { 5-7},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1201186677}
}

Sano, Takashi. A note on norm estimates of the numerical radius. Proc. Japan Acad. Ser. A Math. Sci., Tome 84 (2008) no. 1, pp.  5-7. http://gdmltest.u-ga.fr/item/1201186677/