Norm of an operator with numerical range in a sector

Chi Kwong Li; Kuo Zhong Wang

doi:10.1016/j.laa.2024.11.024

Norm of an operator with numerical range in a sector

Chi Kwong Li, Kuo Zhong Wang^*

^*Corresponding author for this work

Department of Applied Mathematics

Research output: Contribution to journal › Article › peer-review

Abstract

We refine a recent result of Drury concerning the optimal ratio between the norm and numerical radius of a bounded linear operator T with numerical range lying in a sector of a circular disk. In particular, characterization is given to the operators attaining the optimal ratio, and properties of such operators are explored.

Original language	English
Pages (from-to)	173-192
Number of pages	20
Journal	Linear Algebra and Its Applications
Volume	708
DOIs	https://doi.org/10.1016/j.laa.2024.11.024
State	Published - 1 Mar 2025

Keywords

Norm
Numerical radius

Access to Document

10.1016/j.laa.2024.11.024

Cite this

@article{657d086176dd44d380906e047dade3c2,

title = "Norm of an operator with numerical range in a sector",

abstract = "We refine a recent result of Drury concerning the optimal ratio between the norm and numerical radius of a bounded linear operator T with numerical range lying in a sector of a circular disk. In particular, characterization is given to the operators attaining the optimal ratio, and properties of such operators are explored.",

keywords = "Norm, Numerical radius",

author = "Li, {Chi Kwong} and Wang, {Kuo Zhong}",

note = "Publisher Copyright: {\textcopyright} 2024 Elsevier Inc.",

year = "2025",

month = mar,

day = "1",

doi = "10.1016/j.laa.2024.11.024",

language = "English",

volume = "708",

pages = "173--192",

journal = "Linear Algebra and Its Applications",

issn = "0024-3795",

publisher = "Elsevier Inc.",

}

TY - JOUR

T1 - Norm of an operator with numerical range in a sector

AU - Li, Chi Kwong

AU - Wang, Kuo Zhong

PY - 2025/3/1

Y1 - 2025/3/1

N2 - We refine a recent result of Drury concerning the optimal ratio between the norm and numerical radius of a bounded linear operator T with numerical range lying in a sector of a circular disk. In particular, characterization is given to the operators attaining the optimal ratio, and properties of such operators are explored.

AB - We refine a recent result of Drury concerning the optimal ratio between the norm and numerical radius of a bounded linear operator T with numerical range lying in a sector of a circular disk. In particular, characterization is given to the operators attaining the optimal ratio, and properties of such operators are explored.

KW - Norm

KW - Numerical radius

UR - http://www.scopus.com/inward/record.url?scp=85211217512&partnerID=8YFLogxK

U2 - 10.1016/j.laa.2024.11.024

DO - 10.1016/j.laa.2024.11.024

M3 - Article

AN - SCOPUS:85211217512

SN - 0024-3795

VL - 708

SP - 173

EP - 192

JO - Linear Algebra and Its Applications

JF - Linear Algebra and Its Applications

ER -

Norm of an operator with numerical range in a sector

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this