A Generalisation of the Cauchy Integral Formula for Normal Matrices

The Cauchy integral formula says that $$\frac{1}{2{\pi} i} \int\limits_{C} \frac{f( z)}{z - m}\, d z = f(m)$$ if f is holomorphic in a neighbourhood U of ${m \in \mathbb{C}}$ and C is a simple Jordan curve contained in U about m. In this note, we express $$\frac{1}{2{\pi} i} \int\limits_{C} \frac{f( z)}{\det( z I - M)}\, d z$$ as an average over the numerical range co(??(M)) of a normal matrix M, when f is holomorphic in a neighbourhood U of the numerical range of M and C is a simple Jordan curve contained in U about the set ??(M) of eigenvalues of M. The expression is of use in determining the propagation cone of a symmetric hyperbolic system of PDE.     

矩阵对角占优性的推广

本文引入了一类新的对角占优矩阵，并讨论了它与Ｄ０（Ｒ），ＳＤ０（Ｒ）类矩阵的关系．     

Normal Forms of Symplectic Matrices

Abstract In this paper, we prove that for every symplectic matrix M possessing eigenvalues on the unit circle, there exists a symplectic matrix P such that P ⁻¹ MP is a symplectic matrix of the normal forms defined in this paper. Partially supported by the NSF, MCSEC of China, and the Qiu Shi Sci. Tech. Foundation * Associate Member of the ICTP     

Skew-Hadamard Matrices and the Smith Normal Form

We show that the Smith normal form of every skew-Hadamard matrix of order 4m is diag[1,2,...,2, 2m,...,2m,4m]     

关于(0,1)的对称和规范矩阵

给出更多的对于给定行和向量存在（０，１）对称矩阵的等价条件，同时也讨论了（０，１）规范矩阵的情形．     

奇异四元数矩阵的正态及Wishart分布

本文利用拉直算子(vec)和Kronecker积求得了四元数矩阵的实表示矩阵的一些性质,在此基础上利用实矩阵的奇异正态分布密度函数,求出了四元数矩阵的奇异正态分布的密度函数表达式.由此得到四元数矩阵奇异Wishart分布的密度函数表达式.     

The Worst-Case GMRES for Normal Matrices

We study the convergence of GMRES for linear algebraic systems with normal matrices. In particular, we explore the standard bound based on a min-max approximation problem on the discrete set of the matrix eigenvalues. This bound is sharp, i.e. it is attainable by the GMRES residual norm. The question is how to evaluate or estimate the standard bound, and if it is possible to characterize the GMRES-related quantities for which this bound is attained (worst-case GMRES). In this paper we completely characterize the worst-case GMRES-related quantities in the next-to-last iteration step and evaluate the standard bound in terms of explicit polynomials involving the matrix eigenvalues. For a general iteration step, we develop a computable lower and upper bound on the standard bound. Our bounds allow us to study the worst-case GMRES residual norm as a function of the eigenvalue distribution. For hermitian matrices the lower bound is equal to the worst-case residual norm. In addition, numerical experiments show that the lower bound is generally very tight, and support our conjecture that it is to within a factor of 4/π of the actual worst-case residual norm. Since the worst-case residual norm in each step is to within a factor of the square root of the matrix size to what is considered an “average” residual norm, our results are of relevance beyond the worst case. This revised version was published online in July 2006 with corrections to the Cover Date.     

Iteration of Analytic Normal Functions of Matrices

In this paper, the author proves that the classical theorem of Wolff in the theory of complex functions may be extended to the class of operator-valued functions f, where f is an analytic function from the open unit disc \Delta in the complex plane into a family of commutative normal operators on a certain n-dimensional complex Hilbert space, and ||f(z)||<1 holds for every z in \Delta.     

R\'enyi公式的推广

在本文,作为著名的R\''enyi公式(其刻画了标号连通单圈图的计数显式)的自然推广,我们研究了标号匀称$(k+1)$秩$(p,~q)$超单圈的计数问题,给出了如下的计数显式:$$U_{p,~q}^{(k+1)}=\begin{cases} \frac{p!}{2[(k-1)!]^q}\cdot\sum_{t=2}^q \frac{q^{q-t-1}\cdot sgn(tk-2)}{(q-t)!}, & p=qk, \\ 0,& p\neq qk, \end{cases}$$其中$k,~p,~q$均为正整数.     

Density of States and Thouless Formula for Random Unitary Band Matrices

We study the density of states measure for some class of random unitary band matrices and prove a Thouless formula relating it to the associated Lyapunov exponent. This class of random matrices appears in the study of the dynamical stability of certain quantum systems and can be considered as a unitary version of the Anderson model. It is also related with orthogonal polynomials on the unit circle. We further determine the support of the density of states measure and provide a condition ensuring it possesses an analytic density. Communicated by Eugene BogomolnySubmitted 07/11/03, accepted 15/01/04     

规范矩阵乘积迹的一个不等式

本文给出规范矩阵乘积迹的一个新的更强的不等式,推广了陈道琦先生1988年得到的一个著名结果。     

全概率公式的推广及其应用

全概率公式及其思想在概率统计与随机过程中具有重要作用.给出了公式在条件概率下的推广形式与具体应用.同时,得到了独立性条件下的特殊形式.     

格矩阵半群的Euler-Fermat公式

给出并证明格矩阵半群的Euler-Fermat公式:A(n-1)2 1 = A(n-1)2 1 [n], A ∈ Mn(L)其中L是任意的分配格,Mn(L)是L上所有n阶矩阵构成的半群.这是布尔矩阵半群的Euler-Fermat公式的一种推广.     

实规范矩阵的特征值问题

实对称矩阵的特征值问题,无论是低阶稠密矩阵的全部特征值问题,或高阶稀疏矩阵的部分特征值问题,都已有许多有效的计算方法,迄今最重要的一些成果已总结在[5]中。本文利用规范矩阵的一些重要性质将对于Hermite矩阵(特别是对弥矩阵)特征值问题的一些有效算法推广到规范矩阵的特征值问题,由于对复规范阵的推广是简单的,而且实际上常遇到的是实矩阵(这时常要求只用实运算),因此我们着重讨论实规范矩阵的特征值问题。     

An Extension of the Pizzetti Formula for Polyharmonic Functions

We represent the integral over the unit ball B in R ⁿ of any poly-harmonic function u(x) of degree m as a linear combination with constant coefficients of the integrals of its Laplacians ^j u (j = 0,...,m - 1) over any fixed(n - 1)-dimensional hypersphere S() of radius (0 1). In case = 0 theformula reduces to the classical Pizzetti formula. In particular, the cubature formula derived here integrates exactly all algebraic polynomials of degree 2m - 1.     

A Compact Cauchy-Kovalevskaya Extension Formula in Discrete Clifford Analysis

We prove a compact expression for the Cauchy-Kovalevskaya extension in the setting of discrete Clifford analysis; it seamlessly simplifies to the well-know exponential formula in the continuous setting when the discrete step size tends to zero.