非奇H矩阵与M-矩阵的等价条件

本文引进了局部对角占优矩阵的概念，得到了非奇Ｈ矩阵与Ｍ－矩阵的等价条件与判定准则，改进了文［１］的主要结果．     

局部双对角占优矩阵及应用

本文引进了局部双对角占优矩阵的概念，讨论了这类矩阵的性质，给出了局部双对角占优矩阵是广义严格对角占优矩阵的等价表征，得到了Ｍ－矩阵的新表征，推广了［１－１２］的相应结果。     

不可约M－矩阵的刻画（II）

该文给出了（非）奇异Ｚ－矩阵是（非）奇异不可约Ｍ－矩阵的一些充分必要条件．     

奇异M—矩阵的图相容弱正则分裂

设Ａ是奇异Ｍ－矩阵，Ａ＝Ｍ－Ｎ是Ａ的图相容弱正则分裂。本文研究迭代矩阵Ｍ＾－１Ｎ的谱性质，得到与迭代矩阵的指数有关的一个定理：ｉｎｄ０（Ａ）＝ｉｎｄ１（Ｍ＾－１Ｎ）．它推广了Ｈ．Ｓｃｈｎｅｉｄｅｒ和作者的结果。     

非奇H矩阵与M—矩阵的等价表征

引进了局部α－对角占优矩阵的概念,得到了非奇Ｈ矩阵与Ｍ－矩阵的等价表征和判定准则,推广和改进了「１～３」的相应结果。     

奇异M─矩阵的图相容弱正则分裂

设Ａ是奇异Ｍ－矩阵，Ａ＝Ｍ－Ｎ是Ａ的图相容弱正则分裂．本文研究迭代矩阵Ｍ－１Ｎ的谱性质，得到与迭代矩阵的指数有关的一个定理：ｉｎｄ０（Ａ）＝ｉｎｄ１（Ｍ－１Ｎ）．它推广了Ｈ．Ｓｃｈｎｅｉｄｅｒ和作者的结果．     

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．     

‖B~（－1）A‖的估计和H矩阵的充分条件

‖Ｂ~（－１）Ａ‖的估计和Ｈ矩阵的充分条件黄廷祝，游兆永（电子科技大学数学系成都６１００５４）（西安交大数学所西安７１００４９）关键词：范数；Ｈ矩阵；迭代法；矩阵分解ＡＭＳ（１９引）主题分类：６５Ｆ１０；６５Ｆ１５；１５Ａ４８本文讨论ＩＢ－’Ａｌ一和?..     

Hadamard积和酉不变范数不等式

设Ｍｎ，ｍ是ｎ×ｍ复矩阵空间，Ｍｎ≡Ｍｎ，ｎ．对于Ｈｅｒｍｉｔｅ阵Ｇ，Ｈ∈Ｍｎ，ＧＨ表示Ｇ－Ｈ半正定．记Ａ和Ｂ的Ｈａｄａｍａｒｄ积为ＡＢ．本文证明了若Ａ，Ｂ∈Ｍｎ正定，而Ｘ，Ｙ∈Ｍｎ，ｍ任意，则（ＸＡ－１Ｘ）（ＹＢ－１Ｙ）（ＸＹ）（ＡＢ）－１（ＸＹ），ＸＡ－１Ｘ＋ＹＢ－１Ｙ（Ｘ＋Ｙ）（Ａ＋Ｂ）－１（Ｘ＋Ｙ）．这推广和统一了一些现存的结果．设‖·‖为任意酉不变范数，Ｉ是单位矩阵．本文还证明了对于Ｘ∈Ｍｎ，ｍ和Ａ∈Ｍｎ，Ｂ∈Ｍｍ，若ＡＩ，ＢＩ，则函数ｆ（ｐ）＝‖ＡｐＸ＋ＸＢｐ‖在［０，∞）上单调递增．     

求矩阵A^＋的初等变换法

求矩阵Ａ~＋的初等变换法赵昌成（湖北郧阳师专４４１９００）设Ａ是复ｍ×ｎ矩阵，如果ｎ×ｍ矩阵Ｘ满足（１）ＡＸＡ＝Ａ（２）ＸＡＸ＝Ｘ；（３）（ＡＸ）＝ＡＸ；（４）（ＸＡ）＝ＸＡ．则称Ｘ为Ａ的Ｍｏｒｅ－Ｐｅｎｒｏｓｅ广义逆（号表示对矩阵取共轭转置运算）．...     

广义严格对角占优矩阵与非奇M矩阵的判定

１引言Ｍ矩阵是计算数学中应给极其广泛的矩阵类,它出现于经济价值模型矩阵和反网络系统分析的系数矩阵及解某类确定微分方程问题的数值解法中．由于Ｍ矩阵的重要性,讨论Ｍ矩阵及相关的广义对角占优矩阵的判定及性质有着十分重要的意义．本文则是在文［１］～［３］基础上,给出了广义严格对角占优矩阵与非奇Ｍ矩阵几则新的充分条件．拓广了文［１］～［３］的相关结果．２主要结果定义１设Ａ＝（ａｉｊ）,如果存在正对角阵Ｄ,使得ＡＤ为严格对角占优阵,则称Ａ为广义严格对角占优阵．定义２设Ａ＝,Ｍ（Ａ）＝（Ｍｉｊ）,其中,则称Ｓ…     

Equivalence Representation for Nonsingular M-matrices

ＥｑｕｉｖａｌｅｎｃｅＲｅｐｒｅｓｅｎｔａｔｉｏｎｆｏｒＮｏｎｓｉｎｇｕｌａｒＭ－ｍａｔｒｉｃｅｓＳｕｎＹｕｘｉａｎｇ（孙玉祥）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＪｉｌｉｎＴｅａｃｈｅｒ＇ｓＣｏｌｌｅｇｅＪｉｌｉｎ，１３２０１１）Ａｂ...     

On the stability of the incomplete LU-factorizations and characterizations of H-matrices

Summary. Meijerink and van der Vorst [8] have shown that the incomplete LU-factorizations are numerically stable for M-matrices. Varga, Saff and Mehrmann [16] gave some characterizations of the H-matrices by using the incomplete LU-factorizations of them. The purpose of this paper is to show that the incomplete LU-factorizations of an H-matrix are at least as stable as the complete LU-factorizations of its comparison matrix. We give also some new characterizations of the H-matrices in connection with their incomplete LU-factorizations. Received November 12, 1993 / Revised version received May 27, 1994     

双对角占优与非奇M-矩阵的判定

本文利用矩阵B=A A^T的双对角占优性给出了矩阵A为M矩阵的新判定准则，推广了已有的判定定理。实例说明，采用本文定理可以较为容易地得出判定结果，本文给出的判定准则具有简单、方便的特点，与已有的判定准则相比，具有更为广泛的适用范围。     

An incomplete factorization preconditioning method based on modification of element matrices

It is well known that standard incomplete factorization (IC) methods exist for M-matrices [15] and that modified incomplete factorization (MIC) methods exist for weakly diagonally dominant matrices [8]. The restriction to these classes of matrices excludes many realistic general applications to discretized partial differential equations. We present a technique to avoid this problem by making an initial modification already at the element level, followed by the standard IC or MIC factorization of the assembled matrix. This modification ensures weakly diagonally dominant M-matrices and is made in such a way that the condition number of the matrix is only increased by a constant factor independent of the mesh parameterh. Hence the fast convergence of the MICCG method, that is inO(h ^–1/2),h 0 iterations for second order elliptic problems, is preserved.     

Comparison Results Between Preconditioned Jacobi and the AOR Iterative Method

The large scale linear systems with M-matrices often appear in a wide variety of areas of physical,fluid dynamics and economic sciences.It is reported in[1]that the convergence rate of the IMGS method,with the preconditioner I S_α,is superior to that of the basic SOR iterative method for the M-matrix.This paper considers the preconditioned Jacobi(PJ)method with the preconditioner P=I S_α S_β,and proves theoretically that the convergence rate of the PJ method is better than that of the basic AOR method.Numerical examples are provided to illustrate the main results obtained.     

On functions that preserve M-matrices and inverse M-matrices

In earlier works, authors such as Varga, Micchelli and Willoughby, Ando, and Fiedler and Schneider have studied and characterized functions which preserve the M-matrices or some subclasses of the M-matrices, such as the Stieltjes matrices. Here we characterize functions which either preserve the inverse M-matrices or map the inverse M-matrices to the M-matrices. In one of our results we employ the theory of Pick functions to show that if A and B are inverse M-matrices such that B ^?1 ≤ A ^?1, then (B+tI)?1 ≤ (A+tI)?1, for all t?≥?0.     

三对角逆M-矩阵

In this paper we study a class of inverse M-matrices:tridiagonal inverse M-matrices,Graph theory is used to discuss the structure and properties of tridiagonal inverse M-matrices,A sufficient and necessary condtion for a nonnegative tridiagonal matrix to be an inverse M-matrix is given.Finally,it is proved that the set of the inverses of M-matrices with unipathic is closed under Hadamard product.