Results 31 to 40 of about 2,762,818 (340)
On generalized numerical ranges [PDF]
Pacific Journal of Mathematics, 1976 which ||(T- viyι\\ = l/d(υ, W(T)), v£ CLW(T), where CLW(T) is the closure of the numerical range W(T) of Γ, has been generalized by using the concept of generalized numerical ranges due to C. S. Lin. Also it has been shown that the notions of generalized Minkowski distance functionals and generalized numerical ranges arise in a natural way for elements
openaire +3 more sources
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 +2 more
doaj +1 more source
Circularity of the numerical range
Linear Algebra and its Applications, 1994 AbstractAn equivalent condition on a 3-square complex or a 4-square real upper triangular matrix is found for its numerical range to be a circular disk centered at the origin. Sufficient conditions for the circularity of the numerical range of certain sparse matrices are also given in terms of graphs.
Bit-Shun Tam, Mao-Ting Chien
openaire +2 more sources
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
doaj +1 more source
The numerical range of periodic banded Toeplitz operators [PDF]
Adv. Oper. Theory 9, 7 (2024), 2023 We prove that the closure of the numerical range of a $(n+1)$-periodic and $(2m+1)$-banded Toeplitz operator can be expressed as the closure of the convex hull of the uncountable union of numerical ranges of certain symbol matrices. In contrast to the periodic $3$-banded (or tridiagonal) case, we show an example of a $2$-periodic and $5$-banded ...
arxiv +1 more source
Journal of Mathematical Analysis and Applications, 2003 AbstractExistence of the fractional powers is established in Banach algebra setting, in terms of the numerical ranges of elements involved. The behavior of the spectra and (for Hermitian ∗-algebras satisfying some additional hypotheses) the ∗-numerical range under taking these powers also is investigated.
Ilya M. Spitkovsky +2 more
openaire +2 more sources
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.
doaj +1 more source
Sesquilinear version of numerical range and numerical radius
Acta Universitatis Sapientiae: Mathematica, 2017 In this paper by using the notion of sesquilinear form we introduce a new class of numerical range and numerical radius in normed space 𝒱, also its various characterizations are given. We apply our results to get some inequalities.
Moradi Hamid Reza +3 more
doaj +1 more source
Polynomials and Numerical Ranges [PDF]
Proceedings of the American Mathematical Society, 1988 Let A A be an n × n n \times n complex matrix. For 1 ≤ k ≤ n 1 \leq k \leq n we study the inclusion relation for the following polynomial sets related to the matrix A A . (a) The classical numerical range of the k
openaire +2 more sources
Some results on Drazin-Dagger matrices, reciprocal matrices, and conjugate EP matrices [PDF]
Journal of Mahani Mathematical ResearchIn 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 +1 more
doaj +1 more source