实对称矩阵、特征值、特征向量之间的关系及其几何意义的一点注记

本文提出并证明命题:设n 阶实对称矩阵A 的特征值中有一个是单根,其余是n-1重根,且已知属于单根的特征向量,则所有与属于单根的特征向量正交的非零向量都是属于n-1重根的特征向量,进而确定A,且以三阶实对称矩阵为例说明特征值与特征向量的几何意义。     

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.     

因子分析中特征向量和主成分的应用研究

讨论了因子分析的基本思想,结合实例从相关系数矩阵出发,计算其特征根和对应的特征向量,然后给出进行主成分分析的三种方法;进行旋转前后因子载荷矩阵的共同度、累计方差、特征根等多角度比较,深刻揭示因子分析和主成分分析之间的关系.     

化实对称矩阵成对角形的两个技巧

求正交矩阵化实对称矩阵成对角形的方法教材中已给出,为了活跃教学,本文提供两个技巧。 1.曲方程组(λE-A)X~T=0直接解得正交的特征向量。 设λ_0是n阶实对称矩阵A的k重根。对应于λ_0的特征向量由(λ_0E-A)X~T=0给出,这     

实对称矩阵基本定理的存在性证明

对于实对称矩阵A,通过考虑欧氏空间?~n中的连续函数f(X)=X~TAX在一些有界闭集上的最大值,构造相应子空间上的半正定矩阵,进而得到实对称矩阵A的实特征值和相应的特征向量.最终可得实对称矩阵A可以正交相似对角化.     

一类特殊对称矩阵的特征值与特征向量

同济大学《线性代数》第130页例10要求一个正交变换．把二次型化为标准形，其中需要求矩阵的特征值与单位正交特征向量。事实上，这个矩阵R是一种具有特殊对称性的矩阵。这类矩阵的特征问题有如下的一般结论。考虑如下的特殊对称矩阵其中A、B均为m阶实对称阵，u是m维列向量，a是实数。求该类对称矩阵的特征值与特征向量的问题可转化为低阶对称矩阵的相应问题。定理1）设人，…，人是矩阵A－B的特征值，xl，…，X。是对应的单位正交特征向董；u；，…，u。是矩阵A＋B的特征值，y；，…，y。是对应的单位正交特征向量，则人，…，入，户；…     

Householder矩阵的又一特性

给出了Householder矩阵的其它若干性质,利用本文中得到的正交向量组所对应的Householder矩阵的重要性质,解决了形如A=k1H1 k2H2 … knHn(ki∈R,Hi为n阶Householder矩阵,i=1,2,…n)的实对称阵的特性值与特征向量的问题,且任一实对称矩阵A均可表示为上述形式.     

矩阵的特征根与特征向量及其相似对角形的优化求法

研究了矩阵的特征根与特征向量及其相似对角形的优化求法.优化了文[1]的方法,只要对矩阵A的特征矩阵λE-A施行初等变换化为对角形,即可同时求出A的特征根与特征向量,判断A是否可对角化.在A可对角化时,可直接写出相应的可逆矩阵T,使T~(-1)AT为对角形矩阵.     

利用特征矩阵求实对称矩阵的特征向量

本文利用Hamilton-Cayley定理和特征矩阵的性质,给出了求实对称矩阵的特征向量的新方法,并通过例子验证了该方法.     

实对称区间矩阵特征值确界的交错定理及其应用

本文将实对称矩阵特征值的交错定理推广到实对称区间矩阵,给出了实对称区间矩阵特征值确界的交错定理,并应用该定理构造了估计实对称三对角区间矩阵特征值界的算法.文中数值例子表明,本文所给算法与一些现有算法相比在使用范围、计算精度和计算量等方面都具有一定的优越性.     

On least eigenvalues and least eigenvectors of real symmetric matrices and graphs

We give an upper bound for the least eigenvalue of a principal submatrix of a real symmetric matrix with zero diagonal, from which we establish an upper bound for the least eigenvalue of a graph when some vertices are removed using the components of the least eigenvector(s). We give lower and upper bounds for the least eigenvalue of a graph when some edges are removed. We also establish bounds for the components of the least eigenvector(s) of a real symmetric matrix and a graph.     

Perron–Frobenius property of copositive matrices, and a block copositivity criterion

Haynsworth and Hoffman proved in 1969 that the spectral radius of a symmetric copositive matrix is an eigenvalue of this matrix. This note investigates conditions which guarantee that an eigenvector corresponding to this dominant eigenvalue has no negative coordinates, i.e., whether the Perron–Frobenius property holds. Also a block copositivity criterion using the Schur complement is specified which may be helpful to reduce dimension in copositivity checks and which generalizes results proposed by Andersson et al. in 1995, and Johnson and Reams in 2005. Apparently, the latter five researchers were unaware of the more general results by the author precedingly published in 1987 and 1996, respectively.     

实H空间对称线性单调算子固有值问题及应用

本文在实Ｈｉｌｂｅｒｔ空间中讨论了带权算子的对称线性单调算子的固有值问题，得出了最小正固有值及其相应的固有向量的一些相关结论，并给出了它们在某些边值、初边值问题等方面的应用     

Eigenvalue perturbation bounds for Hermitian block tridiagonal matrices

We derive new perturbation bounds for eigenvalues of Hermitian matrices with block tridiagonal structure. The main message of this paper is that an eigenvalue is insensitive to blockwise perturbation, if it is well-separated from the spectrum of the diagonal blocks nearby the perturbed blocks. Our bound is particularly effective when the matrix is block-diagonally dominant and graded. Our approach is to obtain eigenvalue bounds via bounding eigenvector components, which is based on the observation that an eigenvalue is insensitive to componentwise perturbation if the corresponding eigenvector components are small. We use the same idea to explain two well-known phenomena, one concerning aggressive early deflation used in the symmetric tridiagonal QR algorithm and the other concerning the extremal eigenvalues of Wilkinson matrices.     

Characterization of symmetric M-matrices as resistive inverses

We aim here at characterizing those nonnegative matrices whose inverse is an irreducible Stieltjes matrix. Specifically, we prove that any irreducible Stieltjes matrix is a resistive inverse. To do this we consider the network defined by the off-diagonal entries of the matrix and we identify the matrix with a positive definite Schrödinger operator whose ground state is determined by the lowest eigenvalue of the matrix and the corresponding positive eigenvector. We also analyze the case in which the operator is positive semidefinite which corresponds to the study of singular irreducible symmetric M-matrices.     

A bandstructure-invariant deflation for real symmetric matrices

By means of an eigenvector and eigenvalue of a real symmetric matrix A, a unitary matrix U is constructed such that U¹AU deflates A and, moreover, the transformation preserves the bandstructure.     

The most representative shape of a family of curves

Suppose that we are given a family of curves, either continuous or discrete, and we wish to determine a curve that is most representative of the family. Using least squares theory, we find that in both cases we seek the dominant eigenvalue and eigenvector of a symmetric matrix. Numerical approaches to the eigenvalue problem are then given. One involves the standard inverse power method, and the other involves a new differential equation approach. Faddeev's method for obtaining the characteristic polynomial is also employed. Two illustrative examples, one for a family of continuous curves and one for a family of discrete curves, are presented.     

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.     

Global exponential synchronization criterion for switched linear coupled dynamic networks

We in this paper develop a global exponential synchronization stability criterion for switched linear coupled network. By introducing a switching symmetric matrix, we prove that the stability of global exponential synchronization is governed by the largest eigenvalue of this switching symmetric matrix and the largest switching coupling strength. Meanwhile, we give the threshold of switching coupling strength which can make the switched linear network reach global exponential synchronization. Because the proposed criterion is on the basis of the original synchronization definition and the largest eigenvalue of the switching symmetric matrix, therefore, it is convenient to use in verifying global exponential synchronization of dynamic network with switching linear couplings.     

A Variant of the Inverted Lanczos Method

In this note we study a variant of the inverted Lanczos method which computes eigenvalue approximates of a symmetric matrix A as Ritz values of A from a Krylov space of A ^–1. The method turns out to be slightly faster than the Lanczos method at least as long as reorthogonalization is not required. The method is applied to the problem of determining the smallest eigenvalue of a symmetric Toeplitz matrix. It is accelerated taking advantage of symmetry properties of the correspond ng eigenvector.This revised version was published online in October 2005 with corrections to the Cover Date.