实循环矩阵与实对角矩阵相似问题

本文中我们证明了与实对角矩阵相似的每一个实循环矩阵都是对称的．并给出了一个正交变换，使得任意的ｎ×ｎ实循环对称矩阵通过该变换与实对角矩阵相似．     

关于实对称矩阵的基本定理

重新证明了实对称矩阵的基本定理:对于任意一个实对称矩阵A,存在实正交矩阵T,使得T′AT成对角形.     

四元数自共轭矩阵乘积的相似变换

本文证明了下列结果:(i)四元数矩阵A可写成两个自共轭四元数矩阵的乘积A相似于实矩阵A Hermite相似于A~*.(ii)A可写成一个半正定自共轭四元数矩阵与一个自共轭四元数矩阵的乘积A相似于实对角矩阵或者A～diag(D,I_r(×)J_2(O)),其中D是一个实对角矩阵.本文还给出了体上实矩阵AB与BA相似的一个充要条件.     

Oppenheim不等式的一种类似

证明了实对称正定矩阵或实对称半正定矩阵与 M-矩阵的 Hadamard乘积满足实对称正定矩阵 Hadamard乘积的 Oppenheim不等式 .     

广义实对称矩阵及有关性质

给出了广义实对称矩阵的定义,得到的基本运算结果仍然是广义实对称矩阵,并讨论了它的特征值和特征向量.     

正定矩阵的子式阵仍是正定矩阵的一个充要条件

文[2]证明了实对称正定矩阵的子式阵仍然是实对称正定矩阵,文[3]给出了一般的正定矩阵的的概念,本文利用标准型给出了一般正定矩阵的子式阵仍然是正定矩阵的充要条件．     

Über Matrizen mit Semidefinitem Realteil, Imaginärteil oder Polarem Defekt und Ihre Eigenwerte

We give a new short proof using properties of the field of values to show that

a) a complex matrix with only real eigenvalues is either hermitian or has indefinite imaginary part, and

b) one with only purely imaginary eigenvalues is either skew-hermitian or has indefinite real part, while

c) one whose eigenvalues all have absolute value 1 is either unitary or has indefinite polar defect I—TT^*.

Conversely, every skewsymmetric matrix is the skewsymmetric part of some real matrix that is similar to a real diagonal matrix. The corresponding result for complex matrices is found to be false.     

具有实谱值的四元数矩阵的谱值估计

本文给出了具有实谱值的四元数矩阵的定义，得到了一些具有实谱值的四元数矩阵的谱值不等式，这些不等式只涉及到了四元数矩阵的迹的实部和它的平方的迹的实部。     

The robust property of rational strictly positive real matrices

It is shown that not every strictly positive real matrix has robustness, and the necessary and sufficient conditions for a rational strictly positive real matrix with real coefficients to be robust are derived.Institute of Systems Science, Academia Sinica     

四元数向量和矩阵的秩

在四元数和四元数向量、矩阵空间上引入三种不同的实表示法则，将四元数列向量的左右线性相关性问题转换成实数域上向量的线性相关问题，由此获得用实矩阵的秩代替四元数矩阵列左秩和列右秩计算方法，同时得出四元数矩阵可逆的一些充要条件和一些新的四元数行列式定义．     

On the similarity transformation to tridiagonal form

For every real square matrix A there exists a nonsingular real matrix X, for which X^-1AX is a tridiagonal matrix, and under certain conditions X is uniquely determined. Simple proofs are presented for the existence and uniqueness of this transformation.     

Roots of real matrices

An algorithm for computing the roots of a matrix with real elements and the real part of the eigenvalues not zero will be described. The algorithm is based on the sign matrix given in an earlier paper and the projectors of the matrix.     

A necessary and sufficient condition for the stabilisation of a matrix and its principal submatrices

We present a necessary and sufficient condition for the existence of a real diagonal matrix such that its product with a given real square matrix is Hurwitz together with all its principal submatrices. We also give an explicit formula for a matrix which, in particular, supplies all the involved matrices with negative distinct eigenvalues.     

Some properties of the positive real matrix

In this paper, some properties of the rational positive real matrix are discussed by means of coprime fraction of a rational matrix. Some equivalent conditions which are natural extension of the rational positive real function, are given for testing a rational positive real matrix.     

用改进遗传算法求解矩阵实特征值

依据矩阵特征值的分布理论,通过确定矩阵实特征值的分布区域,用实数编码和具有自适应交叉概率和变异概率的遗传算法来求解矩阵实特征值的近似值.仿真结果表明,此算法可以达到一定的精度,具有一定的通用性.并给求矩阵特征值提供了一种快速的方法.     

Matrix representations of octonions and their applications

As is well-known, the real quaternion division algebra ℍ is algebraically isomorphic to a 4-by-4 real matrix algebra. But the real division octonion algebra can not be algebraically isomorphic to any matrix algebras over the real number field ℝ, because is a non-associative algebra over ℝ. However since is an extension of ℍ by the Cayley-Dickson process and is also finite-dimensional, some pseudo real matrix representations of octonions can still be introduced through real matrix representations of quaternions. In this paper we give a complete investigation to real matrix representations of octonions, and consider their various applications to octonions as well as matrices of octonions.     

八元数矩阵的行列式及其性质

赋范的可除代数只有四种:实数R,复数C,四元数日和八元数O.由于八元数关于乘法非交换且非结合,如何对八元数矩阵定义行列式并使其具有较好的运算性质变得非常困难.最近,李兴民和黎丽根据"八元数自共轭矩阵的行列式应为实数"这一数学与物理上的需求,通过选择几个八元数乘积的次序和结合方式,首次给出了八元数行列式的定义.但是,与实数、复数以及四元数的相应的情形比较,如此定义的行列式,其所具备的运算性质较少.本文给出了一种新的八元数行列式的定义,它们具备了尽可能多的运算性质,同时使得"八元数自共轭矩阵的行列式为实数"不证自明.     

Iterative algorithms for solving a class of complex conjugate and transpose matrix equations

This paper is concerned with iterative solutions to a class of complex matrix equations, which include some previously investigated matrix equations as special cases. By applying the hierarchical identification principle, an iterative algorithm is constructed to solve this class of matrix equations. A sufficient condition is presented to guarantee that the proposed algorithm is convergent for an arbitrary initial matrix with a real representation of a complex matrix as tools. By using some properties of the real representation, a convergence condition that is easier to compute is also given in terms of original coefficient matrices. A numerical example is employed to illustrate the effectiveness of the proposed methods.     

用3个向量对构造梁振动系统的刚度矩阵

针对梁的离散化模型的刚度矩阵是五对角矩阵,梁振动反问题的实质是实对称五对角矩阵的特征值反问题.该文利用向量对、Moore-Penrose广义逆给出了实对称五对角矩阵向量对反问题存在唯一解的条件,并结合矩阵分块讨论了双对称五对角矩阵向量对反问题解存在唯一的条件,进而计算了次对角线位置元素为负,其它位置元素均为正的实对称五对角矩阵特征值反问题.由于构造梁的离散模型需要的数据可由测试得到,故而其结果适合于模态分析、系统结构的分析与设计等方面应用.最后给出了数值算例,通过数值讨论说明方法的有效性.     

实正定矩阵的复合矩阵的正定性

本文讨论了实正定矩阵的复合矩阵的正定性，并且给出了实正定矩阵的复合矩阵仍为正定矩阵的一个充要条件.