Selçuk Journal
of
Applied Mathematics
WinterSpring, 2001
Volume 2
Number 1
Research Center
of
Applied Mathematics

SJAM
WinterSpring 2001, Volume 2  Number 1

A modification of the matrix sign function method

Gennadii Demidenko^{1*}, Yuliya Klevtsova^{ 2} 
^{
1
}
Sobolev Institute of Mathematics, SB RAS, Novosibirsk, Russia
email: demidenk@math.nsc.ru
^{2}
Novosibirsk State University, 630090 Novosibirsk, Russia
Received:
March 07, 2001

Summary
This paper is devoted to the dichotomy problem for the matrix spectrum with
respect to the imaginary axis. We consider a method of constructing approximate projections onto invariant subspaces of matrices. The method is a modification of the matrix sign function method. We prove also a theorem on a perturbation for the matrix spectrum.

Key
words
matrix sign function method, projections onto invariant subspaces,
matrix spectrum dichotomy, perturbation of the matrix spectrum

Mathematics Subject Classification (1991):
15A60,
65F15, 65F30, 65F35

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