Results 11 to 20 of about 2,762,818 (340)

On the geometry of numerical ranges [PDF]

Pacific Journal of Mathematics, 1975
M. Radjabalipour, Heydar Radjavi
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Index rank-$k$ numerical range of matrices [PDF]

Journal of Mahani Mathematical Research, 2023
We introduce the $\alpha-$higher rank form of the matrix numerical range, which is a special case of the matrix polynomial version of higher rank numerical range.
Sharifeh Rezagholi, Rouholah Yasini
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The Numerical Range of C*ψ Cφ and Cφ C*ψ

Concrete Operators, 2021
In this paper we investigate the numerical range of C*bφm Caφn and Caφn C*bφm on the Hardy space where φ is an inner function fixing the origin and a and b are points in the open unit disc.
Clifford John, Dabkowski Michael, Wiggins Alan   +2 more
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Further extensions of Hartfiel’s determinant inequality to multiple matrices

Special Matrices, 2021
Following the recent work of Zheng et al., in this paper, we first present a new extension Hartfiel’s determinant inequality to multiple positive definite matrices, and then we extend the result to a larger class of matrices, namely, matrices whose ...
Luo Wenhui
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Investigating the numerical range and q-numerical range of non square matrices [PDF]

Opuscula Mathematica, 2011
A presentation of numerical ranges for rectangular matrices is undertaken in this paper, introducing two different definitions and elaborating basic properties. Further, we extend to the \(q\)-numerical range.
Aikaterini Aretaki, John Maroulas
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On Preserving Properties of Linear Maps on $C^{*}$-algebras [PDF]

Sahand Communications in Mathematical Analysis, 2020
Let $A$ and $B$ be two unital $C^{*}$-algebras and $varphi:A rightarrow B$ be a linear map. In this paper, we investigate the structure of linear maps between two $C^{*}$-algebras that preserve a certain property or relation.
Fatemeh Golfarshchi, Ali Asghar Khalilzadeh   +1 more
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Some Results on Polynomial Numerical Hulls of Perturbed Matrices [PDF]

Sahand Communications in Mathematical Analysis, 2019
In this paper, the behavior of the pseudopolynomial numerical hull of a square complex matrix with respect to structured perturbations and its radius is investigated.
Madjid Khakshour, Gholamreza Aghamollaei
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On partial isometries with circular numerical range

Concrete Operators, 2021
In their LAMA 2016 paper Gau, Wang and Wu conjectured that a partial isometry A acting on ℂn cannot have a circular numerical range with a non-zero center, and proved this conjecture for n ≤ 4. We prove it for operators with rank A = n − 1 and any n.
Wegert Elias, Spitkovsky Ilya
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New class of operators where the distance between the identity operator and the generalized Jordan ∗-derivation range is maximal

Demonstratio Mathematica, 2021
A new class of operators, larger than ∗\ast -finite operators, named generalized ∗\ast -finite operators and noted by Gℱ∗(ℋ){{\mathcal{G {\mathcal F} }}}^{\ast }\left({\mathcal{ {\mathcal H} }}) is introduced, where: Gℱ∗(ℋ)={(A,B)∈ℬ(ℋ)×ℬ(ℋ):∥TA−BT∗−λI ...
Messaoudene Hadia, Mesbah Nadia
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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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