Summary: 1
On an Inverse Eigenvalue Problem for Unitary Hessenberg Matrices
Gregory S. Ammar
Department of Mathematical Sciences
Northern Illinois University
DeKalb, IL 60115 USA
and
Chunyang He
Fachbereich Mathematik
Technische Universit¨at Chemnitz­Zwickau
PSF 964
O­9010 Chemnitz, Germany
ABSTRACT
We show that a unitary upper Hessenberg matrix with positive subdiago­
nal elements is uniquely determined by its eigenvalues and the eigenvalues of a
modified principal submatrix. This provides an analog of a well­known result for
Jacobi matrices.
1. INTRODUCTION
We refer to a real symmetric tridiagonal matrix with positive subdiagonal
entries as a Jacobi matrix. Jacobi matrices are closely connected with

Source: Ammar, Greg - Department of Mathematical Sciences, Northern Illinois University

Collections: Mathematics