English

More accurate numerical radius inequalities (II)

Functional Analysis 2019-07-10 v1

Abstract

In a recent work of the authors, we showed some general inequalities governing numerical radius inequalities using convex functions. In this article, we present results that complement the aforementioned inequalities. In particular, the new versions can be looked at as refined and generalized forms of some well known numerical radius inequalities. Among many other results, we show that f(AA+AA4)01f((1t)B2+tC2)dtf(w2(A)),\left\| f\left( \frac{{{A}^{*}}A+A{{A}^{*}}}{4} \right) \right\|\le \left\| \int_{0}^{1}{f\left( \left( 1-t \right){{B}^{2}}+t{{C}^{2}} \right)dt} \right\|\le f\left( {{w}^{2}}\left( A \right) \right), when AA is a bounded linear operator on a Hilbert space having the Cartesian decomposition A=B+iC.A=B+iC. This result, for example, extends and refines a celebrated result by kittaneh.

Keywords

Cite

@article{arxiv.1907.03944,
  title  = {More accurate numerical radius inequalities (II)},
  author = {Hamid Reza moradi and Mohammad Sababheh},
  journal= {arXiv preprint arXiv:1907.03944},
  year   = {2019}
}

Comments

This article complements our previous work in arXiv:1906.08559

R2 v1 2026-06-23T10:15:36.490Z