Ray nonsingularity of cycle chain matrices

摘要

Ray nonsingular (RNS) matrices are a generalization of sign nonsingular (SNS) matrices from the real field to complex field. The problem of how to recognize ray nonsingular matrices is still open. In this paper, we give an algorithm to recognize the ray nonsingularity for the so called "cycle chain matrices", whose associated digraphs are of certain simple structure. Furthermore, the cycle chain matrices that are not ray nonsingular are classified into two classes according to whether or not they can be majorized by some RNS cycle chain matrices, and the case when they can is characterized.