Krystyna Zietak, "Properties of the strict spectral approximation
of a complex matrix"


The aim of the paper is the approximation of complex matrices with respect
to unitary invariant norms by means of matrices from linear subspaces.
We summarize the properties and characterizations of the strict spectral
approximation which is best in some sense among all spectral approximations 
of a given matrix. We notice  the similarity of the properties of spectral
approximation and of the properties of strict Chebyshev solutions
of overdetermined systems of linear equations.

key words:  matrix approximation,  spectral norm, cp-norm,
overdetermined system, Chebyshev solution.