Results 21 to 30 of about 489,763 (264)
The numerical range of an operator [PDF]
Pacific Journal of Mathematics, 1970 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
openaire +3 more sources
Joint numerical ranges: recent advances and applications minicourse by V. Müller and Yu. Tomilov
Concrete Operators, 2020 We present a survey of some recent results concerning joint numerical ranges of n-tuples of Hilbert space operators, accompanied with several new observations and remarks.
Müller V., Tomilov Yu.
doaj +1 more source
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
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 +1 more source
Journal of Mathematical Analysis and Applications, 2003 Let \({\mathfrak a}\) be a complex Banach algebra with unit \(e\). The algebraic numerical range \(V(a)\) of an element \(a\) in \({\mathfrak a}\) is the set \(\{f(a): f\) is a bounded linear functional on \({\mathfrak a}\) such that \(f(e)= \| f\|=1\}\).
Li, Chi-Kwong +2 more
openaire +2 more sources
On Birkhoff – James and Roberts orthogonality
Special Matrices, 2018 In this paper we present some recent results on characterizations of the Birkhoff-James and the Roberts orthogonality in C*-algebras and Hilbert C*-modules.
Arambašic Ljiljana, Rajic Rajna
doaj +1 more source
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
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
doaj +1 more source
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.
doaj +1 more source
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
doaj +1 more source