矩阵Frobenius标准形的初等变换解法及其应用

矩阵的初等变换在求矩阵的秩、求方阵的逆矩阵、化实对称阵合同于对角阵、求解线性方程组等中均有重要的应用,本文给出了初等变换使方阵相似于Frobenius标准形的方法;该方法运算简单,容易实现,并为求方阵的特征多项式,化方阵为Jordan标准形及求出相应的相似变换阵带来极大的方便。     

关于研究生入学考试试题的一个注记

本文从2018年研究生入学考试的一道选择题出发,探讨了任意两个方阵相似问题.并结合教学实际,给出了判定两个方阵相似的一个简明充要条件.     

关于复方阵的平方根

本刊文 [1]中提出如何判断一个方阵是否存在平方根的问题 .这里 ,我们就 n阶复方阵情形给出三个判别准则 .设 A是 n阶复方阵 ,JA 表示它的若当标准形 ,则存在相似变换矩阵 P,使得 A=PJAP-1 .有关复方阵 A的若当标准形 JA 以及相似变换矩阵P的求法 ,见本刊文 [2 ]或 [3 ] ,本文不再赘述 .定义 1　设 A是 n阶复方阵 ,若存在 n阶复方阵 B,使得 B2 =A,则称 B为 A的平方根 .为书写简便 ,我们用记号 Jr( x) ( r≥ 1)与diag[B1 ,B2 ,… ,Bs]分别表示 r阶若当矩阵和对角块矩阵 :x 1 x 1x∈ Mr( C) ,B1 B2 Bs.用文 [2 ]中给出的计算复…     

半正定复方阵

综述了有关半正定复方阵的主要研究成果，其中包含半正定复方阵在合同下的标准形、半正定复方阵在合同下的全系不变量、半正定复方阵在其Hermite部分及斜Hermite部分之间的Mindowski型行列式不等式以及两个半正定复方阵的，Kronecker乘积仍为半正定的必要且充分条件．     

Jordan标准形的计算与矩阵相似的判定

利用矩阵特征值的代数重数及几何重数的概念,给出计算三阶、四阶复方阵的Jordan标准形的一种新方法;并进一步讨论了三阶、四阶复方阵的相似问题,得到判断任意两个三阶、四阶复方阵相似的充要条件.     

半正定复方阵的Kronecker乘积

本文应用半正定（未必是Ｈｅｒｍｉｔｅ）复方阵在合同下的标准形给出两个半正定（未必是Ｈｅｒｍｉｔｅ）复方阵的Ｋｒｏｎｅｃｋｅｒ乘积为半正定的充要条件     

对称部分为半正定的方阵

所有ｎ阶具有半正定对称部分的方阵的集合记作ＰＳＤｎ．本文给出了ＰＳＤｎ中方阵在合同下的标准形以及ＰＳＤｎ中两个方阵合同的一个充要条件，并给出了ＰＳＤｎ中一个方阵及其对称部分与斜对称部分的主子式间的一个不等式．     

实域中矩阵的几种标准形式及应用

利用矩阵A(λ)的性质,给出了方阵A在实域内的几种标准形式,并讨论了其在微分方程中的应用.     

若当标准形的计算

在线性代数与矩阵论中,一个重要问题是如何将复数域C上的任意n阶方阵A相似到尽可能简单的方阵J．也就是说：寻找适当的可逆方阵P,使P^-1AP=J．     

Jordan标准形过渡矩阵求法的补充条件

用反例证明了用方阵的特征向量逆推Jordan链构作Jordan标准形过渡矩阵的方法在理论上不成立,并给出了使这个方法成立的补充条件.     

三阶矩阵的平方根

给出3×3矩阵的平方根公式，并通过实例阐明我们的方法，完善了有关文献中的某些结果．     

相伴于平方根算子的Hp空间

本文利用椭圆算子的平方根所生成的热核给出了Hp空间的极大函数刻画.     

Square Root Functional Equation on Positive Cones

A square root functional equation on positive cones of C＇-algebras is introduced and its solution and Hyers-Ulam-Rassias stability are investigated.     

On the Square Root of an H-matrix with Positive Diagonal Elements

This paper proves that for an H-matrix with positive diagonal elements there exists one and only one square root which is also an H-matrix with positive diagonal elements. An algorithm approaching the square root is proposed.     

The Square Root Problem and Aluthge transforms of weighted shifts

In this paper we consider the following question. When does there exist a square root of a probability measure supported on ? This question is naturally related to subnormality of weighted shifts. The main result of this paper is that if μ is a finitely atomic probability measure having at most 4 atoms, then μ has a square root, i.e., there exists a measure ν such that (* means the convolution) if and only if the Aluthge transform of a subnormal weighted shift with Berger measure μ is subnormal. As an application of them, we give non‐trivial, large classes of probability measures having a square root. We also prove that there are 6 and 7‐atomic probability measures which don't have any square root. Our results have a connection to the following long‐open problem in Operator Theory: characterize the subnormal operators having a square root.     

相伴于平方根算子的Hp空间

本文利用椭圆算子的平方根所生成的热核给出了H^p空间的极大函数刻画。     

The Kato Square Root Problem for Mixed Boundary Value Problems

We solve the Kato square root problem for second order ellipticsystems in divergence form under mixed boundary conditions onLipschitz domains. This answers a question posed by Lions in1962. To do this we develop a general theory of quadratic estimatesand functional calculi for complex perturbations of Dirac-typeoperators on Lipschitz domains.     

Convergence of Numerical Approximation for Jump Models Involving Delay and Mean-Reverting Square Root Process

The mean-reverting square root process with jump has been widely used as a model on the financial market. Since the diffusion coefficient in the model does not satisfy the linear growth condition and local Lipschitz condition, we can not examine its properties by traditional techniques. To overcome the difficulties, we develop several new techniques to examine the numerical method of jump models involving delay and mean-reverting square root. We show that the numerical approximate solutions converge to the true solutions. Finally, we apply the convergence to examine a path-dependent option price and a bond in the financial pricing.     

三阶矩阵的平方根

给出3×3矩阵的平方根公式,并通过实例阐明我们的方法,完善了有关文献中的某些结果.     

Strong-Type Inequality for Convolution with Square Root of the Poisson Kernel

The boundary behavior of convolutions with Poisson kernel and with square root of the Poisson kernel is essentially different. The former has only a nontangential limit. The latter involves convergence over domains admitting the logarithmic order of tangency with the boundary (P. Sjögren, J.-O. Rönning). This result was generalized by the authors to spaces of homogeneous type. Here we prove the boundedness in L ^p, p > 1, of the corresponding maximal operator. Only a weak-type inequality was known before.