Summary: An Efficient QR Algorithm for a Hessenberg
Submatrix of a Unitary Matrix
Gregory S. Ammar1
, William B. Gragg2
, and Chunyang He3
Department of Mathematical Sciences, Northern Illinois University, DeKalb, IL
60115 USA. firstname.lastname@example.org
Department of Mathematics, Naval Postgraduate School, Monterey, CA 93943
USA. bill email@example.com
Department of Mathematics and Statistics, University of MissouriKansas City,
5100 Rockhill Road, Kansas City, MO 641102499 USA.
Dedicated to Clyde Martin on the occasion of his sixtieth birthday.
Summary. We describe an efficient procedure for implementing the Hessenberg
QR algorithm on a class of matrices that we refer to as subunitary matrices. This
class includes the set of Szego-Hessenberg matrices, whose characteristic polynomials
are Szego polynomials, i.e., polynomials orthogonal with respect to a measure on