摘要
1 IntroductionLet A∈C<sup>n×n</sup>, B∈C<sup>n×n</sup>.We say B is a square root of A if A=B×B i.e.A=B<sup>2</sup>.It is well-known that any symmetric positive definite matrix exists one and only onesquare root which is a symmetric positive definite matrix,too（e.g.see[5]）.Higham[4]studied carefully the relation of a real nonsingular matrix between its real square rootsand its eigenvalues.Alefeld and Schneider[1]pointed out that for any nonsingular M-ma-trix there is one and only one M-matrix as its square root.In this paper,we study on
基金
The second author is supported by Xiamen University,China
