An extension of several essential numerical radius inequalities of $2\times 2$ off-diagonal operator matrices
Mohammed Al-Dolat, Imad Jaradat, Dumitru Bǎleanu · Advances in Difference Equations · 2020
In this work, we provide upper and lower bounds for the numerical radius of an \(n\times n\) off-diagonal operator matrix, which extends some results by Abu-Omar and Kittaneh (Stud. Math. 216:69–75, 2013 ; Linear Algebra Appl. 468:18–26, 2015 ; Rocky Mt. J. Math. 45(4):1055–1065, 2015 ), and Paul and Bag (Appl. Math. Comput. 222:2731–2943, 2013 ).