关于复矩阵乘积的正定性

两复正定矩阵之和必是复正定矩阵,但其积未必是复正定矩阵.研究了复矩阵之积的正定性,给出了复矩阵之积为复正定矩阵的一系列判定条件,获得了一些新的结果,改进并推广了K y Fan T aussky定理及Fe jer定理.     

加强p除环上自共轭矩阵的几个定理

本文将实对称矩阵和复Hermiitian环矩阵,以及更特殊的正定与半正定矩阵的一些较为深入的定理推广到加强p除上矩阵中来.     

复矩阵的亚半正定性

复亚半正定矩阵是 Hermite正定阵的推广 ,研究了它的 Kronecker积、Hadamard积和行列式理论 ,将实对称阵的 Schur定理、华罗庚定理、Minkowski不等式、Ky-Fan不等式、Ostrowski-Taussky不等式推广到了一类非 Hermite复矩阵上 ,扩大了 Minkowski不等式的指数范围 ,削弱了华罗庚不等式的条件 .     

关于复正定矩阵的判定

研究了复矩阵的正定性 ,给出了复正定矩阵的一系列判定条件 ,获得了一些新的结果 ,改进并推广了著名的 Hadam ard不等式、Fejer定理及郭忠的结果 ,削弱了华罗庚不等式的条件 .     

复矩阵的亚半正定性

复亚半正定矩阵是Hermite正定阵的推广,研究了它的Kronecker积,Hadamard积和行列式理论,将实对称阵的Schur定理,华罗庚定理,Minkowski不等式,Ky-Fan不等式,Ostrowski-Taussky不等式推广到一类非Hermite复矩阵上,扩大了Minkowski不等式的指数范围,削弱了华罗庚不等式的条件。     

自共轭四元数矩阵的行列式的展开定理及其应用

本文是在[1]文的基础上,证明自共轭四元数矩阵 A 的行列式‖A‖的展开定理,而当 A 为实对称矩阵或复 Hermitian 矩阵时,‖A‖的展开式即与通常的行列式|A|的展开式一致.并由此进一步得出 A 的特征多项式 f(λ)就是 A 的特征矩阵的行展开式,从而得到 f(λ)的直接计算法,且由此又得到正定与半正定自共轭矩阵的另一等价命题,完善了[2]中(?)4的结果.还有一些关于实、复正定与半正定矩阵的重要定理,也可应用展开定理把它们加以推广.     

复正定矩阵的充要条件

本文研究Hermite正定矩阵、实正定矩阵的推广概念复正定矩阵,给出了复方阵复正定性的一些充分必要条件。     

次正定复矩阵次Schur补的一些性质

利用复矩阵的Schur补和次正定性,研究了次正定复矩阵的次Schur补的一些性质,得到了次正定复矩阵次Schur补的几个行列式不等式,将相关文献的相应结果由次正定次Hermite矩阵推广到次正定复矩阵.     

(N,1)-广义正定矩阵

本文对被屠伯埙称为亚正定的矩阵类进行了推广,即给出了(n,1)-广义正定矩阵的概念,进而得到了(n,1)-广义正定矩阵的一系列性质,最后将关于正定阵的Hadamard乘积的Schur定理及华罗庚定理推广到(n,1)-广义正定矩阵.     

复正定矩阵的Minkowski不等式

建立了复正定矩阵的几个行列式不等式,将正定Ｈｅｒｍｉｔｅ阵的Ｍｉｎｋｏｗｓｋｉ不等式、 Ｏｓｔｒｏｗｓｋｉ－Ｔａｕｓｓｋｙ不等式推广到了复正定矩阵上,推广改进了一些文献的结果．     

Singular numbers of contractions in spaces with an indefinite metric and Yamamoto's theorem

A theorem of Yamamoto on singular numbers of matrices is extended to G-bounded matrices.     

A note on linear preservers of certain ranks of tensor products of matrices

In this note, we give a simple proof as well as an extension of a very recent result of B. Zheng, J. Xu and A. Fosner concerning linear maps between vector spaces of complex square matrices that preserve the rank of tensor products of matrices by using a structure theorem of R. Westwick on linear maps between tensor product spaces that preserve non-zero decomposable elements.     

两个Hermitian矩阵的Hadamard乘积的特征值估计

Schur定理规定了半正定矩阵的Hadamard乘积的所有特征值的整体界限,Eric Iksoon lm在同样的条件下确定了每个特征值的特殊的界限,本文给出了Hermitian矩阵的Hadamard乘积的每个特征值的估计,改进和推广了I.Schur和Eric Iksoon Im的相应结果。     

On an operator inequality

Jensen's operator inequality characterizes operator convex functions of two variables (F. Hansen, Proc. Amer. Math. Soc. 125 (1997) 2093–2102). We give a simplified proof of this theorem formulated for matrices.     

Poncelet's theorem, Sendov's conjecture, and Blaschke products

By connecting Blaschke products, unitary dilations of matrices, numerical range, Poncelet's theorem and interpolation, we extend and simplify Gau and Wu's work (Gau and Wu (2004) [10]). We look at Blaschke products' role in the Sendov conjecture.     

Convergence of Rump's method for inverting arbitrarily ill-conditioned matrices

In this paper, the problem of inverting regular matrices with arbitrarily large condition number is treated in double precision defined by IEEE 754 floating point standard. In about 1984, Rump derived a method for inverting arbitrarily ill-conditioned matrices. The method requires the possibility to calculate a dot product in higher precision. Rump's method is of theoretical interest. Rump made it clear that inverting an arbitrarily ill-conditioned matrix in single or double precision does not produce meaningless numbers, but contains a lot of information in it. Rump's method uses such inverses as preconditioners. Numerical experiments exhibit that Rump's method converges rapidly for various matrices with large condition numbers. Why Rump's method is so efficient for inverting arbitrarily ill-conditioned matrices is a little mysterious. Thus, to prove its convergence is an interesting problem in numerical error analysis. In this article, a convergence theorem is presented for a variant of Rump's method.     

中心对称与中心交错矩阵几何

应用对称(交错)矩阵几何基本定理,本文证明了域上中心对称(交错)矩阵几何基本定理.     

On the construction of cospectral nonisomorphic bipartite graphs

In this article, we construct bipartite graphs which are cospectral for both the adjacency and normalized Laplacian matrices using the notion of partitioned tensor products. This extends the construction of Ji, Gong, and Wang [9]. Our proof of the cospectrality of adjacency matrices simplifies the proof of the bipartite case of Godsil and McKay's construction [4], and shows that the corresponding normalized Laplacian matrices are also cospectral. We partially characterize the isomorphism in Godsil and McKay's construction, and generalize Ji et al.'s characterization of the isomorphism to biregular bipartite graphs. The essential idea in characterizing the isomorphism uses Hammack's cancellation law as opposed to Hall's marriage theorem used by Ji et al.     

Taussky定理推广与应用

本文在Ｃａｓｓｉｎｉ卵形域上推广了Ｔａｕｓｓｋｙ定理。所得结果修正了Ｂｒａｕｅｒ定理,作为应用给出不可约双对角占优矩阵非奇异的充要条件,最后把基本结果推广到分块矩阵上。