A note on classes of structured matrices with elliptical type numerical range

2021 ◽  
pp. 1-9
Author(s):  
Natália Bebiano ◽  
Susana Furtado
Keyword(s):  
Numerical Range ◽  
Structured Matrices

A new method for approximation of closed convex subsets of B(H)

Filomat ◽  
2017 ◽  
Vol 31 (19) ◽  
pp. 6005-6013
Author(s):  
Mahdi Iranmanesh ◽  
Fatemeh Soleimany
Keyword(s):  
Best Approximation ◽  
Numerical Range ◽  
New Method ◽  
C Algebra ◽  
Convex Subsets

In this paper we use the concept of numerical range to characterize best approximation points in closed convex subsets of B(H): Finally by using this method we give also a useful characterization of best approximation in closed convex subsets of a C*-algebra A.

a-Numerical range on $$C^*$$-algebras

Positivity ◽  
2021 ◽  
Author(s):  
Abdellatif Bourhim ◽  
Mohamed Mabrouk
Keyword(s):  
Numerical Range ◽  
C Algebras

On the maximal numerical range of the bimultiplication M2,A,B

2021 ◽  
pp. 1-8
Author(s):  
Abderrahim Baghdad ◽  
Chraibi Kaadoud Mohamed
Keyword(s):  
Numerical Range

scholarly journals Global Properties of Eigenvalues of Parametric Rank One Perturbations for Unstructured and Structured Matrices

2021 ◽  
Vol 15 (3) ◽  
Author(s):  
André C. M. Ran ◽  
Michał Wojtylak
Keyword(s):  
Unit Circle ◽  
Structured Matrices ◽  
Additional Structure ◽  
General Properties ◽  
Global Properties ◽  
Classes Of Matrices ◽  
Rank One

AbstractGeneral properties of eigenvalues of $$A+\tau uv^*$$ A + τ u v ∗ as functions of $$\tau \in {\mathbb {C} }$$ τ ∈ C or $$\tau \in {\mathbb {R} }$$ τ ∈ R or $$\tau ={{\,\mathrm{{e}}\,}}^{{{\,\mathrm{{i}}\,}}\theta }$$ τ = e i θ on the unit circle are considered. In particular, the problem of existence of global analytic formulas for eigenvalues is addressed. Furthermore, the limits of eigenvalues with $$\tau \rightarrow \infty $$ τ → ∞ are discussed in detail. The following classes of matrices are considered: complex (without additional structure), real (without additional structure), complex H-selfadjoint and real J-Hamiltonian.

scholarly journals $L$-ideals and numerical range preservation

1977 ◽  
Vol 21 (2) ◽  
pp. 365-373 ◽  
Author(s):  
C. K. Chui ◽  
P. W. Smith ◽  
R. R. Smith ◽  
J. D. Ward
Keyword(s):  
Numerical Range
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