Results 21 to 30 of about 463,320 (265)

Volterra operator norms : a brief survey

Moroccan Journal of Pure and Applied Analysis, 2023
In this expository article, we discuss the evaluation and estimation of the operator norms of various functions of the Volterra operator.
Ransford Thomas
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Investigations of the numerical range of a operator matrix

Vestnik Samarskogo Gosudarstvennogo Tehničeskogo Universiteta. Seriâ: Fiziko-Matematičeskie Nauki, 2014
We consider a $2\times2$ operator matrix $A$ (so-called generalized Friedrichs model) associated with a system of at most two quantum particles on ${\rm d}$-dimensional lattice.
Tulkin Kh Rasulov, Elyor B Dilmurodov
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Inverse Numerical Range and Determinantal Quartic Curves

Mathematics, 2020
A hyperbolic ternary form, according to the Helton–Vinnikov theorem, admits a determinantal representation of a linear symmetric matrix pencil. A kernel vector function of the linear symmetric matrix pencil is a solution to the inverse numerical range ...
Mao-Ting Chien, Hiroshi Nakazato
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On some reciprocal matrices with elliptical components of their Kippenhahn curves

Special Matrices, 2021
By definition, reciprocal matrices are tridiagonal n-by-n matrices A with constant main diagonal and such that ai,i+1ai+1,i= 1 for i = 1, . . ., n − 1.
Jiang Muyan, Spitkovsky Ilya M.
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The Numerical Range of 6 Χ 6 Irreducible Matrices [PDF]

Al-Rafidain Journal of Computer Sciences and Mathematics, 2007
In this paper, we consider the problem of characterizing the numerical range of 6 by 6 irreducible matrices which have line segments on their boundary.
Ahmed Sabir
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Spatial numerical ranges of elements of subalgebras of C0(X)

International Journal of Mathematics and Mathematical Sciences, 2000
When A is a subalgebra of the commutative Banach algebra C0(X) of all continuous complex-valued functions on a locally compact Hausdorff space X, the spatial numerical range of element of A can be described in terms of positive measures.
Sin-Ei Takahasi
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Some results on Drazin-Dagger matrices, reciprocal matrices, and conjugate EP matrices [PDF]

Journal of Mahani Mathematical Research
In this paper, a class of matrices, namely, Drazin-dagger matrices, in which the Drazin inverse andthe Moore-Penrose inverse commute, is introduced. Also, some properties of the generalized inverses of these matrices, are investigated.
Mahdiyeh Mortezaei, Gholamreza Aghamollaei   +1 more
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On 3-by-3 row stochastic matrices

Special Matrices, 2023
The known constructive tests for the shapes of the numerical ranges in the 3-by-3 case are further specified when the matrices in question are row stochastic. Auxiliary results on the unitary (ir)reducibility of such matrices are also obtained.
Pham Nhi, Spitkovsky Ilya M.
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Generalization of numerical range of polynomial operator matrices

Tikrit Journal of Pure Science, 2023
Suppose that  is a polynomial matrix operator where  for , are  complex matrix and let  be a complex variable. For an  Hermitian matrix , we define the -numerical range of polynomial matrix of  as , where .
Darawan Zrar Mohammed, Ahmed Muhammad
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Some results on generalized finite operators and range kernel orthogonality in Hilbert spaces

Demonstratio Mathematica, 2021
Let ℋ{\mathcal{ {\mathcal H} }} be a complex Hilbert space and ℬ(ℋ){\mathcal{ {\mathcal B} }}\left({\mathcal{ {\mathcal H} }}) denotes the algebra of all bounded linear operators acting on ℋ{\mathcal{ {\mathcal H} }}.
Mesbah Nadia, Messaoudene Hadia, Alharbi Asma   +2 more
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