Results 11 to 20 of about 2,500,610 (287)
Numerical Range and Quadratic Numerical Range for Damped Systems [PDF]
, 2017 We prove new enclosures for the spectrum of non-selfadjoint operator matrices associated with second order linear differential equations $\ddot{z}(t) + D \dot{z} (t) + A_0 z(t) = 0$ in a Hilbert space.
Jacob, Birgit +3 more
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Some constants related to numerical ranges [PDF]
SIAM Journal on Matrix Analysis and Applications, 2016 In an attempt to progress towards proving the conjecture the numerical range W (A) is a 2--spectral set for the matrix A, we propose a study of various constants. We review some partial results, many problems are still open. We describe our corresponding
Crouzeix, Michel
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Computing the q-Numerical Range of Differential Operators
Journal of Applied Mathematics, 2020 A linear operator on a Hilbert space may be approximated with finite matrices by choosing an orthonormal basis of thez Hilbert space. In this paper, we establish an approximation of the q-numerical range of bounded and unbounnded operator matrices by ...
Ahmed Muhammad, Faiza Abdullah Shareef
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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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Essential numerical range and $C$-numerical range for unbounded operators [PDF]
Studia Mathematica, 2022 Consider an unbounded operator \(T\) on a Hilbert space \(\mathcal{H}\). The authors introduce a new type of essential numerical range for \(T\), called \(W_{e5}(T)\) (essential numerical range of type 5). They show, for instance, that \(W_{e5}(T)\) is closed, convex, and contains the essential spectrum \(\sigma_e(T)\).
Hefti, Nicolas, Tretter, Christiane
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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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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 +2 more
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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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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 joint numerical ranges [PDF]
Pacific Journal of Mathematics, 1978 The joint numerical status of commuting bounded operators Ai and A2 on a Hubert space is defined as {{φiA^y φ(A2)) such that φ is a state on the C*-algebra generated by Ax and A2}. It is shown that if At and A2 are commuting normal operators then their joint numerical status equals the closure of their joint numerical range.
Buoni, John J., Wadhwa, Bhushan L.
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