一般线性方法的线性与非线性稳定性间的关系

１．引言１９６３年,Ｄａｈｌｑｕｉｓｔ以一类线性问题为模型提出了Ａ－稳定性概念,此后有关如何判断方法是否Ａ－稳定或确定其稳定域的研究十分活跃,袁兆鼎等~［１］中对此有详细的讨论．Ｂｕｒｒａｇｅ与Ｂｕｔｃｈｅｒ［２］以一类非线性问题为模型,就一般线性方法引入了代数稳定性概念．Ｂｕｔｃｈｅｒ［４］探讨了代数稳定性与Ａ－稳定性间的内在联系．为确保代数稳定性蕴涵Ａ－稳定性,Ｂｕｔｃｈｅｒ［５］进一步要求代数稳定性定义中涉及的矩阵Ｇ是正定的。然而这样一来,正如李寿佛［６］中指出的那样,许多ＡＮ稳定且按［４…     

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…     

Riccati微分方程的可积条件

Ｉｎ１９９８,ＺｈａｏＬｉｎｌｏｎｇ［１］ｏｂｔａｉｎｅｄｔｈｅｉｎｔｅｇｒａｂｌｅｃｏｎｄｉｔｉｏｎ：Ｒ＝１αγＰｅ２∫（Ｑ－βＤ）ｄｘ　　　（α,β,γｉｓｃｏｎｓｔ）．（１）ＦｏｒＲｉｃｃａｔｉｅｑｕａｔｉｏｎ：ｙ′＝ｐ（ｘ）ｙ２＋Ｑ（ｘ）ｙ＋Ｒ（ｘ）　　（ＰＲ≠０）．（２）　　Ｈｅｒｅｔｈｅｎｅｗｉｎｔｅｇｒａｂｌｅｃｏｎｄｉｔｉｏｎｓｉｓｇｉｖｅｎ：Ｌ［ｙ０］＝１αγＰｅ２∫（Ｑ＋２ｙ０ｐ－βＤ）ｄｘ．（３）Ｌ［ＡＢ＋ｙ０］＝１αγ（ＡＢ）２Ｌ［ｙ０］ｅ２∫（２ＢＡＬ［ｙ０］＋Ｑ＋２ｙ…     

关于正定矩阵的几个问题

本文推广了文［１］的主要定理，给出了用低阶矩阵判定高阶矩阵正定的判定定理，同时给出了矩阵方程ＡＸ＝Ｂ的反问题在正定矩阵类中解存在的充要条件及解的一般形式．     

秩(AB)≤min[秩(A),秩(B)]的一种证法

对于公式秩（ＡＢ）≤ｍｉｎ［秩（Ａ）,秩（Ｂ）］,本文结合线性方程组给出一种简捷的证法．引理如果线性方程组ＡＸ＝θ的解都是ＢＸ＝θ的解,则秩（Ａ）≥秩（Ｂ）．证不妨设ＡＸ＝θ的基础解系含有ｎ－秩（Ａ）个线性无关解,ＢＸ＝θ的基础解系含有ｍ－秩（Ｂ）个...     

离散时间代数Riccati方程的解矩阵的下界与上界

本文讨论离散时间代数Ｒｉｃｃａｔｉ方程ＡＴＸＡ－Ｘ－（ＡＴＸＢ＋Ｌ）（Ｒ＋ＢＴＸＢ）＾－１（ＬＴ＋ＢＴＸＡ）＋Ｑ＝０的唯一对称正定解的上界和下界。     

代数Riccati方程可稳解的条件数

１．引言 关于代数Ｒｉｃｃａｔｉ方程（ＡＲＥ）的研究是大量的．从数值角度看,有关数值方法,扰动理论的研究已比较深入．而关于条件数理论的研究则还不多［３］,［６］． Ｒｙｅｒｓ［１］研究了时连续代数 Ｒｉｃｃａｔｉ方程可稳解的条件数; Ｋｅｎｎｅｙ和 Ｈｅｗｅｒ［３］讨论了时连续代数 Ｒｉｃｃａｔｉ方程（以下简称 ＣＴＡＲＥ）可稳解的敏度分析,给出了一阶扰动界,引进了条件数; Ｓｕｎ［６］从最佳向后扰动理论角度研究了时离散代数Ｒｉｃｃａｔｉ方程（以下简称ＤＴＡＲＥ）可稳解的条件数;徐树方［８］针对 ＣＴＡ…     

广义严格对角占优矩阵的判定

１引言设Ａ＝（ａｉｊ）Ｃｎｘｎ,若对每一ｉＮ＝｛１,２,…,ｎ｝都有则称Ａ为对角占优矩阵,记为ＡＤυ;若（１）式中每一不等号都是严格的,则称Ａ为严格对角占优矩阵,记为ＡＤ．若存在正对角阵Ｘ使ＡＸＤυ（或ＡＸＤ）,则称Ａ为广义（或广义严格）对角占优矩阵;记为ＡＤΥ（或ＡＤ）．广义严格对角占优矩阵的判定在计算数学和矩阵论的研究中占有重要的地位,文［１］和［２］分别定义了α－对角占优矩阵和双对角占优矩阵,讨论了广义严格对角占优矩阵的判定及性质,本文引进了α双对角占优矩阵的概念,得到了广义严格对角占优矩…     

按环路α-连对角占优阵及应用

１．引言与记号 利用矩阵的对角占优性研究矩阵的特征值分布和非奇Ｈ矩阵的判定,是数值代数的重要课题．［１］－［４］给出了利用 Ｏｓｔｒｏｗｓｋｉ定理及连对角占优性判定非奇 Ｈ－矩阵的最新成果．本文引入按环路α－连对角占优概念,给出了非奇Ｈ－矩阵的判定条件及等价表征,简化了计算,改进与推广了［１］－［９］的相应结果． 设Ａ＝．Γ（Ａ）表 Ａ的方向图,其顶点集及弧集分别记作 Ｖ（Ａ）及 Ｅ（Ａ）,ｅｉｊ表从顶点ｉ到顶点 ｊ的弧, Ｃ（Ａ）表 Γ（Ａ）中非平凡环路集合．对任意固定 α Ｅ［０,１］还记＊ｋ伪行、列足…     

任意体上的双矩阵分解与矩阵方程

本文给出了任意体上具有相同行数或相同列数的双矩阵分解定理；利用此定理，给出了任意体上的矩阵方程ＡＸＢ＋ＣＹＤ＝Ｅ及［Ａ１ＸＢ１，Ａ２ＸＢ２］＝［Ｅ１；Ｅ２］有解的充要条件及其一般解的表达式．     

LONG-TIME BEHAVIOR OF A CLASS OF REACTION DIFFUSION EQUATIONS WITH TIME DELAYS

The present paper devotes to the long-time behavior of a class of reaction diffusion equations with delays under Dirichlet boundary conditions. The stability and global attractability for the zero solution are provided, and the existence, stability and attractability for the positive stationary solution are also obtained.     

二阶系统边值问题的正解

以关于非线性全连续算子的锥不动点定为工具,研究二阶系统边值问题,在不假定ｆ,ｇ单调的情况下,得出了上述问题存在正解的若干充分条件。     

一类非线性差分方程正解的不存在性

本文研究一类非线性差分方程及其对偶方程,给出了方程不存在正解的充分条件,所得结论改进了[1]的结果。     

不稳定型二阶中立型方程正解的存在性与有界振动

本文研究一类不稳定型二阶中立型微分方程正解的存在性与有界振动．证明了在一定条件下不稳定型二阶中立型方程总存在无界正解，并给出了保证其方程的一切有界解都振动的充分条件，改进了文［１，２］中的有关条件．     

SUFFICIENT CONDITIONS FOR THE EXISTENCE OF PERIODIC SOLUTIONS OF A AUTONOMOUS DIFFERENTIAL SYSTEM

ＳＵＦＦＩＣＩＥＮＴＣＯＮＤＩＴＩＯＮＳＦＯＲＴＨＥＥＸＩＳＴＥＮＣＥＯＦＰＥＲＩＯＤＩＣＳＯＬＵＴＩＯＮＳＯＦＡＡＵＴＯＮＯＭＯＵＳＤＩＦＦＥＲＥＮＴＩＡＬＳＹＳＴＥＭＨｕａｎｇＬｉｈｏｎｇ（黄立宏）ＹｕＪｉａｎｓｈｅ（庚建设）（Ｄｅｐａｒｔｍｅｎ...     

EXISTENCE OF POSITIVE PERIODIC SOLUTION TO A CLASS OF NONAUTONOMOUS DIFFERENTIAL EQUATION WITH IMPULSES AND DELAY

In this paper, by fixed point theorem of Krasnoselskii, we study the positive pe- riodic solution to a class of nonautonomous differential equation with impulses and delay. Firstly, definition of periodic solution and some lemmas are stated. Then some results on the existence of positive periodic solution to the equation are obtained.     

Viscosity solutions for second order integro-differential equations without monotonicity condition: the probabilistic approach

In this paper, we establish a new existence and uniqueness result of a continuous viscosity solution for integro-partial differential equation (IPDE in short). The novelty is that we relax the so-called monotonicity assumption on the driver which is classically assumed in the literature of viscosity solutions of equation with non-local terms. Our method strongly relies on the link between IPDEs and backward stochastic differential equations with jumps for which we already know that the solution exists and is unique for general drivers. In the second part of the paper, we deal with the IPDE with obstacle and we obtain similar results.     

EXISTENCE AND UNIQUENESS OF POSITIVE SOLUTIONS TO A CLASS OF SEMILINEAR ELLIPTIC SYSTEMS

In this paper an existence and uniqueness theorem of positive solutions to a class of semilinear elliptic systems is proved. Also, a necessary condition for the existence of the positive solution is obtained. As the application of the main theorem, two examples are given.     

THE EXISTENCE OF MULTIPLE POSITIVE SOLUTION OF NON-AUTONOMOUS NONLINEAR NEUTRAL DIFFERENCE EQUATION

In this paper, by using the fixed point index theory, we obtain an existence criteria for multiple positive solution of non-autonomous nonlinear neutral difference equation. We extend the results in [1].     

THE EXISTENCE OF MULTIPLE POSITIVE SOLUTION OF NONLINEAR NEUTRAL DIFFERENCE EQUATION

1IntroductionRecently,anumber0fmeth0dswereempl0yedf0r0btainingp0sitivesolu-tionstodifferenceequations,includingc0mparis0nprinciples,Schaudertypefixedp0inttheorem,Banach'scontractionprinciple,methods0fsuper-andlower-s0luti0ns,themethods0fpositive0perators,andso0n[1-4].Inthispa-per,wewillutilizethefixedpointindextheoryt00btainanexistencecriteriafOrmu1tiplep0sitivesolutionsofn0nlinearneutraldifferenceequationwheren,bi(15z5m1)andry(15j5m2)arep0sitiveinteger,{ci(k)}7=,(l5i5ml)and{pj(k)}7=,(15j5m2)…