let $p(lambda)$ be an $n$-square complex matrix polynomial, and $1 leq k leq n$ be a positive integer. in this paper, some algebraic and geometrical properties of the $k$-numerical range of $p(lambda)$ are investigated. in particular, the relationship between the $k$-numerical range of $p(lambda)$ and the $k$-numerical range of its companion linearization is stated. moreover, the $k$-numerical ...

In this note we characterize polynomial numerical hulls of matrices $A in M_n$ such that$A^2$ is Hermitian. Also, we consider normal matrices $A in M_n$ whose $k^{th}$ power are semidefinite. For such matriceswe show that $V^k(A)=sigma(A)$.

let ‎x be an ‎‎n-‎‎‎‎‎‎square complex matrix with the ‎cartesian decomposition ‎‎x = a + i ‎b‎‎‎‎‎, ‎where ‎‎a ‎and ‎‎b ‎are ‎‎‎n ‎‎times n‎ ‎hermitian ‎matrices. ‎it ‎is ‎known ‎that ‎‎$vert x vert_p^2 ‎leq 2(vert a vert_p^2 + vert b vert_p^2)‎‎‎$, ‎where ‎‎$‎p ‎‎geq 2‎$‎ ‎and ‎‎$‎‎vert . vert_p$ ‎is ‎the ‎schatten ‎‎‎‎p-norm.‎ ‎‎ ‎‎in this paper‎, this inequality and some of its improvements ...

most of river engineering problems are complicated and need to be analyzed by three dimensional models of flow and sediment transport. considering the fact that computers and numerical methods with great ability of flow and sediment transport simulation are developing quickly, using numerical modeling by engineers is inevitable. nevertheless, before application, numerical models need to be veri...

In this talk I will discuss some instances in quantum computing where numerical range techniques arise. I will also try to formulate some open problems. Elliptical range theorems for generalized numerical ranges of quadratic operators Speaker Chi-Kwong Li, William and Mary, [email protected] Co-authors Yiu-Tung Poon, Iowa State University, [email protected]; Nung-Sing Sze, University of Connect...

In quantum computing and quantum control, the investigation of the C-numerical range is of great importance. One relevant optimization problem can be represented as maximizing the trace function R (

It is shown that the result of Tso-Wu on the elliptical shape of the numerical range of quadratic operators holds also for the essential numerical range. The latter is described quantitatively, and based on that sufficient conditions are established under which the c-numerical range also is an ellipse. Several examples are considered, including singular integral operators with the Cauchy kernel...

The numerical range of an n× n matrix polynomial P (λ) = Amλ m + Am−1λ m−1 + . . . + A1λ + A0 is defined by W (P ) = {λ ∈ C : x∗P (λ)x = 0, x ∈ C, x 6= 0}. For the linear pencil P (λ) = Iλ− A, the range W (P ) coincides with the numerical range of matrix A, F (A) = {x∗Ax : x ∈ C, x∗x = 1}. In this paper, we obtain necessary conditions for the origin to be a boundary point of F (A). As a consequ...