Advances in Difference Equations (Jul 2020)
An extension of several essential numerical radius inequalities of 2 × 2 $2\times 2$ off-diagonal operator matrices
Abstract
Abstract In this work, we provide upper and lower bounds for the numerical radius of an n × n $n\times n$ 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).
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