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In this paper, we improve the famous Reid Inequality related to linear operators. Some monotony results for positive operators are also established with a different approach from what is known in the existing literature. Lastly, Reid and…

Functional Analysis · Mathematics 2017-07-12 Souheyb Dehimi , Mohammed Hichem Mortad

Optimal matrices for problems involving the matrix numerical radius often have fields of values that are disks, a phenomenon associated with partial smoothness. Such matrices are highly structured: we experiment in particular with the…

Optimization and Control · Mathematics 2020-05-01 X. Y. Han , Adrian S. Lewis

We obtain upper and lower bounds for the Davis-Wielandt radius of bounded linear operators defined on a complex Hilbert space, which improve on the existing ones. We also obtain bounds for the Davis-Wielandt radius of operator matrices. We…

Functional Analysis · Mathematics 2024-08-14 Pintu Bhunia , Aniket Bhanja , Santanu Bag , Kallol Paul

Let $A$ be a positive bounded operator on a Hilbert space $\big(\mathcal{H}, \langle \cdot, \cdot\rangle \big)$. The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\rangle$, $x, y\in\mathcal{H},$ induces a seminorm…

Functional Analysis · Mathematics 2021-07-23 M. S. Moslehian , Q. Xu , A. Zamani

We study Bohr type inequalities within the framework of fractional calculus. Using Riemann Liouville fractional differential and integral operators, we establish generalized Bohr radii for analytic functions in the unit disk, including the…

Complex Variables · Mathematics 2025-09-26 Adesanmi Mogbademu , Ismaila Amusa

The vast use of computers on scientific numerical computation makes the awareness of the limited precision that these machines are able to provide us an essential matter. A limited and insufficient precision allied to the truncation and…

Numerical Analysis · Computer Science 2009-11-13 B. O. Rodrigues , L. A. C. P. da Mota , L. G. S. Duarte

The conventional rounding error analysis provides worst-case bounds with an associated failure probability and ignores the statistical property of the rounding errors. In this paper, we develop a new statistical rounding error analysis for…

Numerical Analysis · Mathematics 2025-11-04 Yiming Fang , Li Chen

We prove some eigenvalue inequalities for positive semidefinite matrices partitioned into four blocks. The inradius of the numerical range of the off-diagonal block contributes to these estimates. Some related norm inequalities are given…

Functional Analysis · Mathematics 2021-12-01 Jean-Christophe Bourin , Eun-Young Lee

Several unitarily invariant norm inequalities and numerical radius inequalities for Hilbert space operators are studied. We investigate some necessary and sufficient conditions for the parallelism of two bounded operators. For a finite rank…

Functional Analysis · Mathematics 2024-04-03 Pintu Bhunia

To extend the Euclidean operator radius, we define $w_p$ for an $n$-tuples of operators $(T_1,\ldots, T_n)$ in $\mathbb{B}(\mathscr{H})$ by $w_p(T_1,\ldots,T_n):= \sup_{\| x \| =1} \left(\sum_{i=1}^{n}| \langle T_i x, x \rangle |^p…

Functional Analysis · Mathematics 2015-02-03 M. S. Moslehian , M. Sattari , K. Shebrawi

In this paper we introduce a new technique for proving norm inequalities in operator ideals with an unitarily invariant norm. Among the well known inequalities which can be proved with this technique are the L\"owner-Heinz inequality,…

Operator Algebras · Mathematics 2008-08-19 Gabriel Larotonda

The research on spectral inequalities for discrete Schrodinger Operators has proved fruitful in the last decade. Indeed, several authors analysed the operator's canonical relation to a tridiagonal Jacobi matrix operator. In this paper, we…

Functional Analysis · Mathematics 2013-12-09 Arman Sahovic

This paper investigates new properties of $q$-numerical ranges for compact normal operators and establishes refined upper bounds for the $q$-numerical radius of Hilbert space operators. We first prove that for a compact normal operator $T$…

Functional Analysis · Mathematics 2025-12-17 Mohammad H. M. Rashid

In several papers of 2013 - 2016, Guglielmi and Protasov made a breakthrough in the problem of the joint spectral radius computation, developing the invariant polytope algorithm which for most matrix families finds the exact value of the…

Numerical Analysis · Mathematics 2020-06-23 Thomas Mejstrik

In this article we prove new inequalities for the generalized and the joint spectral radius of bounded sets of positive operators on Banach function and sequence spaces, in particular some inequalities for positive kernel operators that…

Functional Analysis · Mathematics 2023-11-07 Katarina Bogdanović

The purpose of this note is to present upper bounds estimations for the numerical radius of a products and Hadamard products of special matrices, including sectorial and accretive-dissipative matrices.

Rings and Algebras · Mathematics 2022-07-19 Mohammad Alakhrass

We completely characterize the Crawford number attainment set and the numerical radius attainment set of a bounded linear operator on a Hilbert space. We study the intersection properties of the corresponding attainment sets of numerical…

Functional Analysis · Mathematics 2020-01-28 Debmalya Sain , Arpita Mal , Pintu Bhunia , Kallol Paul

We obtain weighted mixed inequalities for operators associated to a critical radius function. We consider Schr\"odinger Calder\'on-Zygmund operators of $(s,\delta)$ type, for $1<s\leq \infty$ and $0<\delta \leq 1$. We also give estimates of…

Analysis of PDEs · Mathematics 2022-08-10 Fabio Berra , Gladis Pradolini , Pablo Quijano

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…

Functional Analysis · Mathematics 2024-09-30 Chi-Kwong Li , Kuo-Zhong Wang

In this paper, several significant upper bounds for the numerical radius and $a$-numerical radius of an element in a $\mathcal{C}^*$-algebra are obtained using Orlicz functions. Many well-known results are obtained from our findings,…

Operator Algebras · Mathematics 2024-11-08 Saikat Mahapatra , Riddhick Birbonshi , Arnab Patra