M_3(F_p)的拟相合分类

基于有限结合环同构分类之需,在本文中我们定义了方阵之微别于相合关系的拟相合关系,决定了素域 F_p 上3×3方阵的拟相合分类,并举出了一个全体代表团.     

拟似然非线性模型中MQLE的弱相合性的充分条件

拟似然非线性模型包括广义线性模型作为一个特殊情形.给出了拟似然非线性模型中极大拟似然估计的弱相合性的一些充分条件,其中矩的条件要弱于文献中极大拟似然估计的强相合性的条件.     

正定方阵的张量积

给出了正定方阵的合同根概念，并利用它，刻画了多个正定方阵的张量积仍为正定方阵的充要条件．     

二阶方阵的平方根和三角方阵的三角平方根

二阶方阵的平方根和三角方阵的三角平方根胡结梅（南昌航空工业学院基础一部３３００３４）定义设Ａ是一个ｎ阶方阵，若存在ｎ阶方阵Ｂ，使Ｂ２＝Ａ，则称方阵Ｂ是方阵Ａ的一个平方根．以ｄｅｔＡ表示方阵Ａ的行列式，则由定义得：ｄｅｔＢ＝±ｄｅｔＡ．下面的定理１给出...     

也谈方阵的平方根

文[1]讨论了二阶方阵的平方根和三角方阵的三角平方根问题,但其结论有误．这里指出其错误并给出正确的定理．定义1设A是一个n阶方阵,若存在n阶方阵B,使B2=A,则称方阵B为方阵A的平方根．若有Bm=A,则称B为A的m次方根．文[1]给出如下定理：上（下）三角方阵存在上（下）三角方阵的平方根．对上述定理,文[1]没有给出一般证明,仅以三阶上三角方阵为例来证．但可惜的是,即使这样一个特殊情况的证明仍有漏洞,结论并不成立．例如不存在上三角方阵的平方根．事实上,对任意上三角方阵可以验证,均不存在上三角平方根．我们有如下定理：…     

除环上无限方阵的逆方阵

本文探讨了除环上无限方阵的逆方阵,得到了除环上无限方阵存在左（或右）逆方阵的充要条件．     

拟变分不等式解集的极小本质集及应用

引入了拟变分不等式解集的极小本质集的概念，并证明了每个拟变分不等式(满足一定条件)的解集至少存在一个极小本质集．作为应用，还证明了大多数(在Baire分类意义下)拟-似变分不等式问题的解集是稳定的；每个拟-似变分不等式(满足一定条件)的解集至少存在一个本质连通区．     

固定设计情形下回归函数小波估计的泛相合性

本文引入固定设计情形下回归函数小波估计的泛相合性概念，证明了此小波估计的泛相合性。     

除环上无限方阵的分解

对除环上无限方阵的逆方阵作了简单讨论,证明了除环上无限方阵的分解定理．     

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．     

Hadamard matrices with few distinct types

The notion of type of quadruples of rows is proven to be useful in the classification of Hadamard matrices. In this paper, we investigate Hadamard matrices with few distinct types. Among other results, the Sylvester Hadamard matrices are shown to be characterized by their spectrum of types.     

Relative eigenvalue and singular value perturbations of scaled diagonally dominant matrices

The paper derives improved relative perturbation bounds for the eigenvalues of scaled diagonally dominant Hermitian matrices and new relative perturbation bounds for the singular values of symmetrically scaled diagonally dominant square matrices. The perturbation result for the singular values enlarges the class of well-behaved matrices for accurate computation of the singular values. AMS subject classification (2000)  65F15     

平方非正的符号矩阵的平方中负元个数

本文给出了一个符号矩阵A当A^2非正时A^2中负元个数N－(A^2)的上,下界,并确定相应的极矩阵。     

Core–EP inverse

In this work, we introduce a notion of ‘core–EP inverse’ for a square matrix which is not essentially of index one. This extends the notion of ‘core inverse’, which was initially defined for the matrices of index one. The properties of matrices having ‘core–EP inverse’ and ‘core–EP generalized inverse’ are studied, and obtained a formula to compute the core–EP generalized inverse from a particular linear combination of minors of given matrix.     

Construction of Weighing Matrices W(17, 9) Having the Intersection Number 8

It is unknown( [1], [2], [4] ) whether there exists a weighing matrix W(17,9) or not. The intersection number of W(17,9) is 6 or 8. We completed the classification of weighing matrices W(17, 9) having the intersection number 8. These matrices are classified into 925 non-equivalent classes. We shall show eight representative weighing matrices only together with their automorphism groups and g-distributions. Of these eight matrices, two have the same g-distribution.     

Factoring matrices into the product of two matrices

Linear algebra of factoring a matrix into the product of two matrices with special properties is developed. This is accomplished in terms of the so-called inverse of a matrix subspace which yields an extended notion for the invertibility of a matrix. The product of two matrix subspaces gives rise to a natural generalization of the concept of matrix subspace. Extensions of these ideas are outlined. Several examples on factoring are presented. AMS subject classification (2000)  15A23, 65F30     

Classification of skew‐Hadamard matrices of order 32 and association schemes of order 31

Using a backtracking algorithm along with an essential change to the rows of representatives of known 13 710 027 equivalence classes of Hadamard matrices of order 32, we make an exhaustive computer search feasible and show that there are exactly 6662 inequivalent skew‐Hadamard matrices of order 32. Two skew‐Hadamard matrices are considered SH ‐equivalent if they are similar by a signed permutation matrix. We determine that there are precisely 7227 skew‐Hadamard matrices of order 32 up to SH ‐equivalence. This partly settles a problem posed by Kim and Solé. As a consequence, we provide the classification of association schemes of order 31.     

整数环上矩阵平方和的两个新结论

本文利用 F2 上方阵为平方矩阵的充要条件 ,证明了 :1任一阶数为偶数的整数矩阵可表示成 5个平方次幂整数矩阵之和 ;2任一整数矩阵可表示成 6个平方次幂整数矩阵之和 ,从而改进了文 [2 ,3 ]的主要结论 .     

An improved method for the computation of the Moore-Penrose inverse matrix

In this article we provide a fast computational method in order to calculate the Moore-Penrose inverse of singular square matrices and of rectangular matrices. The proposed method proves to be much faster and has significantly better accuracy than the already proposed methods, while works for full and sparse matrices.     

Inversion and canonization of block matrices

The paper is concerned with the problem of inverting block matrices to which the well-known Frobenius— Schur formulas are not applicable. These can be square matrices with four noninvertible square or rectangular blocks as well as square or rectangular matrices with two blocks. With regard to rectangular matrices, the results obtained are a further step in the development of the canonization method, which is used for solving arbitrary matrix equations.