scholarly journals Positive functionals and Hessenberg matrices

2018 ◽  
Vol 147 (3) ◽  
pp. 1097-1108
Author(s):  
Jean B. Lasserre ◽  
Mihai Putinar
Keyword(s):  
Hessenberg Matrices ◽  
Positive Functionals

scholarly journals On the similarity to nonnegative and Metzler Hessenberg forms

2021 ◽  
Vol 10 (1) ◽  
pp. 1-8
Author(s):  
Christian Grussler ◽  
Anders Rantzer
Keyword(s):  
Standard Form ◽  
Complete Characterization ◽  
Nonnegative Matrices ◽  
Positive Systems ◽  
Third Order ◽  
Hessenberg Form ◽  
Hessenberg Matrices ◽  
Open Question ◽  
Order Continuous

Abstract We address the issue of establishing standard forms for nonnegative and Metzler matrices by considering their similarity to nonnegative and Metzler Hessenberg matrices. It is shown that for dimensions n 3, there always exists a subset of nonnegative matrices that are not similar to a nonnegative Hessenberg form, which in case of n = 3 also provides a complete characterization of all such matrices. For Metzler matrices, we further establish that they are similar to Metzler Hessenberg matrices if n 4. In particular, this provides the first standard form for controllable third order continuous-time positive systems via a positive controller-Hessenberg form. Finally, we present an example which illustrates why this result is not easily transferred to discrete-time positive systems. While many of our supplementary results are proven in general, it remains an open question if Metzler matrices of dimensions n 5 remain similar to Metzler Hessenberg matrices.

scholarly journals Representation of doubly infinite matrices as non-commutative Laurent series

2017 ◽  
Vol 5 (1) ◽  
pp. 250-257 ◽  
Author(s):  
María Ivonne Arenas-Herrera ◽  
Luis Verde-Star
Keyword(s):  
Laurent Series ◽  
Infinite Matrices ◽  
General Properties ◽  
Hessenberg Matrices ◽  
Diagonal Representation

Abstract We present a new way to deal with doubly infinite lower Hessenberg matrices based on the representation of the matrices as the sum of their diagonal submatrices. We show that such representation is a simple and useful tool for computation purposes and also to obtain general properties of the matrices related with inversion, similarity, commutativity, and Pincherle derivatives. The diagonal representation allows us to consider the ring of doubly infinite lower Hessenberg matrices over a ring R as a ring of Laurent series in one indeterminate, with coefficients in the ring of R-valued sequences that don’t commute with the indeterminate.

scholarly journals Convergence of the shifted $QR$ algorithm for unitary Hessenberg matrices

2001 ◽  
Vol 71 (240) ◽  
pp. 1473-1497 ◽  
Author(s):  
Tai-Lin Wang ◽  
William B. Gragg
Keyword(s):  
Hessenberg Matrices ◽  
Qr Algorithm

TheQ R algorithm for real hessenberg matrices

1970 ◽  
Vol 14 (3) ◽  
pp. 219-231 ◽  
Author(s):  
R. S. Martin ◽  
G. Peters ◽  
J. H. Wilkinson
Keyword(s):  
Hessenberg Matrices

scholarly journals Positive functionals and oscillation criteria for second order differential systems

1979 ◽  
Vol 22 (3) ◽  
pp. 277-290 ◽  
Author(s):  
Garret J. Etgen ◽  
Roger T. Lewis
Keyword(s):  
Differential Equation ◽  
Hilbert Space ◽  
Second Order ◽  
Linear Operators ◽  
The Self ◽  
Differential Systems ◽  
Bounded Linear ◽  
Positive Functionals ◽  
Image Position ◽  
Adjoint Operators

Let ℋ be a Hilbert space, let ℬ = (ℋ, ℋ) be the B*-algebra of bounded linear operators from ℋ to ℋ with the uniform operator topology, and let ℒ be the subset of ℬ consisting of the self-adjoint operators. This article is concerned with the second order self-adjoint differential equation

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