Numerical ranges of weighted shift matrices
โ Scribed by Ming Cheng Tsai; Pei Yuan Wu
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 250 KB
- Volume
- 435
- Category
- Article
- ISSN
- 0024-3795
No coin nor oath required. For personal study only.
๐ SIMILAR VOLUMES
Let A be a 3-by-3 weighted shift matrix with weights {s 1 , s 2 }. The q-numerical radius of A is found as an implicit function in q, s 1 , s 2 .
We show that an n-by-n companion matrix A can have at most n line segments on the boundary NW (A) of its numerical range W(A), and it has exactly n line segments on NW (A) if and only if, for n odd, A is unitary, and, for n even, A is unitarily equivalent to the direct sum A 1 โ A 2 of two (n/2)-by-
A Banach algebraic approach is proposed to study the asymptotic bchaviour of the numerical ranges of certain (finite) approximation matrices of {infinite) operators. The approach works for large classes of approximation methods; it is examined in detail here for the finite sections of Toeplitz opera