On upper and lower bounds of the numerical radius and an equality condition

Takeaki Yamazaki. "On upper and lower bounds of the numerical radius and an equality condition." Studia Mathematica 178.1 (2007): 83-89. <http://eudml.org/doc/284877>.

@article{TakeakiYamazaki2007,
abstract = {We give an inequality relating the operator norm of T and the numerical radii of T and its Aluthge transform. It is a more precise estimate of the numerical radius than Kittaneh's result [Studia Math. 158 (2003)]. Then we obtain an equivalent condition for the numerical radius to be equal to half the operator norm.},
author = {Takeaki Yamazaki},
journal = {Studia Mathematica},
keywords = {numerical radius; Aluthge transform; normaloid operators},
language = {eng},
number = {1},
pages = {83-89},
title = {On upper and lower bounds of the numerical radius and an equality condition},
url = {http://eudml.org/doc/284877},
volume = {178},
year = {2007},
}

TY - JOUR
AU - Takeaki Yamazaki
TI - On upper and lower bounds of the numerical radius and an equality condition
JO - Studia Mathematica
PY - 2007
VL - 178
IS - 1
SP - 83
EP - 89
AB - We give an inequality relating the operator norm of T and the numerical radii of T and its Aluthge transform. It is a more precise estimate of the numerical radius than Kittaneh's result [Studia Math. 158 (2003)]. Then we obtain an equivalent condition for the numerical radius to be equal to half the operator norm.
LA - eng
KW - numerical radius; Aluthge transform; normaloid operators
UR - http://eudml.org/doc/284877
ER -