TY - JOUR

T1 - Linear Maps Preserving Regional Eigenvalue Location

AU - Johnson, Charles R.

AU - Li, Chi Kwong

AU - Rodman, Leiba

AU - Spitkovsky, Ilya

AU - Pierce, Stephen

N1 - Funding Information:
2~artiallysu pported by NSF Grant DMS-8900922. 3~artiallysu pported by NSF Grant DMS-9000839. 4~artiallsyu pported by NSF Grant DMS-9101143. 5~artiallysu pported by NSF Grant DMS-9007048. The fifth author gratefully acknowledges the assistance of the Department of Mathematics at the College of William and Mary, where this research was done while he was on sabbatical leave.

PY - 1992/10/1

Y1 - 1992/10/1

N2 - Let M(n,C) be the vector space of n × n complex matrices and let G(r,s,t) be the set of all matrices in M(n,C) having r eigenvalues with positive real part, s eigenvalues with negative real part and t eigenvalues with zero real part. In particular, G(0,n,0) is the set of stable matrices. We investigate the set of linear operators on M(n,C) that map G(r,s,t) into itself. Such maps include, but are not always limited to similarities, transposition, and multiplication by a positive constant. The proof of our results depends on a characterization of nilpotent matrices in terms of matrices in a particular G(r,s,t), and an extension of a result about the existence of a matrix with prescribed eigenstructure and diagonal entries. Each of these results is of independent interest. Moreover, our characterization of nilpotent matrices is sufficiently general to allow us to determine the preservers of many other “inertia classes.”.

AB - Let M(n,C) be the vector space of n × n complex matrices and let G(r,s,t) be the set of all matrices in M(n,C) having r eigenvalues with positive real part, s eigenvalues with negative real part and t eigenvalues with zero real part. In particular, G(0,n,0) is the set of stable matrices. We investigate the set of linear operators on M(n,C) that map G(r,s,t) into itself. Such maps include, but are not always limited to similarities, transposition, and multiplication by a positive constant. The proof of our results depends on a characterization of nilpotent matrices in terms of matrices in a particular G(r,s,t), and an extension of a result about the existence of a matrix with prescribed eigenstructure and diagonal entries. Each of these results is of independent interest. Moreover, our characterization of nilpotent matrices is sufficiently general to allow us to determine the preservers of many other “inertia classes.”.

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U2 - 10.1080/03081089208818168

DO - 10.1080/03081089208818168

M3 - Article

AN - SCOPUS:84963333603

VL - 32

SP - 253

EP - 264

JO - Linear and Multilinear Algebra

JF - Linear and Multilinear Algebra

SN - 0308-1087

IS - 3-4

ER -