Exact Solution of a Linear Difference Equation in a Finite Number of Steps

An exact solution of a linear difference equation in a finite number of steps has been obtained. This refutes the conventional wisdom that a simple iterative method for solving a system of linear algebraic equations is approximate. The nilpotency of the iteration matrix is the necessary and sufficient condition for getting an exact solution. The examples of iterative equations providing an exact solution to the simplest algebraic system are presented.

ON THE BOUNDEDNESS AND PERIODICITY OF THESOLUTIONS OF A CERTAIN VECTOR DIFFERENTIALEQUATION OF THIRD-ORDER

There are given sufficient conditions for the ultimate boundedness of solutions and for the existence of periodic solutions of a certain vector differential equation of third-order.

Flat Solutions of Some Non-Lipschitz Autonomous Semilinear Equations May be Stable for N≥3

The authors prove that flat ground state solutions(i.e. minimizing the energy and with gradient vanishing on the boundary of the domain) of the Dirichlet problem associated to some semilinear autonomous elliptic equations with a strong absorption term given by a non-Lipschitz function are unstable for dimensions N = 1, 2 and they can be stable for N ≥ 3 for suitable values of the involved exponents.

Closed-form Solutions to the Matrix Equation AX-EXF=BY with F in Companion Form

A closed-form solution to the linear matrix equation AX-EXF = BY with X and Y unknown and matrix F being in a companion form is proposed, and two equivalent forms of this solution are also presented. The results provide great convenience to the computation and analysis of the solutions to this class of equations, and can perform important functions in many analysis and design problems in descriptor system theory. The results proposed here are parallel to and more general than our early work about the linear matrix equation AX-XF = BY .

EXTENDABILITY OF SOLUTIONS FOR THE LINEAR SYSTEM OF ELLIPTIC TYPE EQUATIONS

The solutions of linear system of elliptic type equations with first order isdiscussed by using the method of several complex analysis and, a series of newextended results of the solutions for the system of elliptic type are obtained.

Modelling the Dynamical State of the Projected Primary and Secondary Intra-Solution-Particle Movement System of Efavirenz In-Vivo

This work seeks to describe intra-solution particle movement system. It makes use of data obtained from simulations of patients on efavirenz. A system of ordinary differential equations is used to model movement state at some particular concentration. The movement states’ description is found for the primary and secondary level. The primary system is found to be predominantly an unstable system while the secondary system is stable. This is derived from the state of dynamic eigenvalues associated with the system. The saturated solution-particle is projected to be stable both for the primary potential and secondary state. A volume conserving linear system has been suggested to describe the dynamical state of movement of a solution particle.

Non-Traveling Wave Solutions for the (1 + 1)-Dimensional Burgers System by Riccati Equation Mapping Approach

Starting from the symbolic computation system Maple and Riccati equation mapping approach and a linear variable separation approach, a new family of non-traveling wave solutions of the (1 + 1)-dimensional Burgers system is derived.

实对称矩阵正交特征向量的一种新解法

为克服“只在给定向量组的条件下,才能求得正交向量组”的局限性,利用特征向量和正交的定义及齐次线性方程组的非零解求解方法,给出实对称矩阵对应于重特征值的正交特征向量的一种新的求解方法。研究表明,该方法可以有效地减少计算量,并可以直接写出实对称矩阵对应于重特征值的正交特征向量。

A Generalized Block-by-block Method for the System of Linear Volterra Integral Equations of the Second Kind

In this paper, we provide a generalized block-by-block method for constructing block-by-block systems to solve the system of linear Volterra integral equations of the second kind, and then deduce some of the special cases. Compared with the expansion method and He＇s homotopy perturbation method, respectively numerical examples are given to certify the effectiveness of the method. The results show that the block-by-block method is very effective, simple, and of high accuracy in solving the system of linear Volterra integral equations of the second kind.

探讨线性方程组求解问题

对于线性方程组,只有在方程的个数等于未知量的个数,系数行列式不等于零的情况下,才可以使用克莱姆法则求得,也可以使用逆矩阵法求得。而对于一般的线性方程组,如何判定它是否有解、解是否唯一,以及在解不唯一的情况下,又该如何求出它的解。这个问题的解决,对理论和实际都具有十分重要的意义。以下以矩阵为工具,探求一般线性方程组解的情况和解的问题。

EVANS FUNCTIONS AND INSTABILITY OF A STANDING PULSE SOLUTION OF A NONLINEAR SYSTEM OF REACTION DIFFUSION EQUATIONS

In this paper, we consider a nonlinear system of reaction diffusion equa- tions arising from mathematical neuroscience and two nonlinear scalar reaction diffusion equations under some assumptions on their coefficients. The main purpose is to couple together linearized stability criterion （the equivalence of the nonlinear stability, the linear stability and the spectral sta- bility of the standing pulse solutions） and Evans functions to accomplish the existence and instability of standing pulse solutions of the nonlinear system of reaction diffusion equations and the nonlinear scalar reaction diffusion equa- tions. The Evans functions for the standing pulse solutions are constructed explicitly.

常数变易法在微分方程求解中的应用探究

常数变易法是解常微分方程行之有效的一种方法,是拉格朗日历经十一年研究的一种特殊的变量代换法。为探究常数变易法的教学拓展,将常数变易法应用于求解线性微分方程组和高阶线性微分方程,通过常数变易过程,给出简洁推演,建立通解公式,并以典型示例,阐明了公式的实际操作过程。

线性方程组的基础解系

本文研究了线性方程组的基础解系.

线性微分方程的有限差分法求解周期正解

为了提高线性微分方程在求解计算中的性能,提出了线性微分方程的有限差分法求解周期正解。证明了线性微分方程的有限差分格式与能量守恒的离散规则是等价关系,分析了线性微分方程差分格式的正性和周期性,实现了基于有限差分法的线性微分方程求解周期正解。最后通过数值实验的方式,得出与传统差分法求解线性微分方程的周期正解相比,不仅满足了正性要求,还满足了周期性要求。

大型稀疏线性方程组的数值解法

在许多利用经典算法求线性方程组的数值解的过程中,系数矩阵中的零元素对计算结果没有影响,也就没有存储的必要。如果是大型稀疏线性方程组,这样可以节省大量的存储空间。为此,提出一种在MATLAB语言环境中仅储存系数矩阵中非零元素的方法:利用3个1维数组储存系数矩阵中的非零元素及其在矩阵中的位置(行号,列号)。在编程时,忽略零元素参与的运算,可使计算量大大减少。这2个方面的改进使得利用经典算法求解大型稀疏线性方程组成为可能。借助于Jacobi迭代法进行的一系列数值实验,验证了这一探索的可行性。

Excel VBA在数值计算教学中的应用研究--以Jacobi、Seidel、Sor为例

文章在Excel VBA二次开发平台下开发了线性方程组求解的迭代法小工具,实现了在Excel界面输入有限参数的前提下快速自动计算线性方程组的数值解,同时将每一步的计算公式在E x c e 1中展示出来。采用迭代法小工具计算线性方程组的数值解不仅能够提高求解线性方程组的效率,同时能帮助学生理解Jacobi,Seide1,Sor三种算法的原理及提高学习兴趣。

线性代数方程组正交化列处理法

给出对任意的n×m阶相容性或不相容性线性代数方程组均有效的一种新的迭代算法 .证明了算法求解过程 .在经过m次迭代后 ,必然求得该方程组的理论上精确的解或最小二乘解 .分析了该算法的计算复杂度。

线性方程组迭代解的随机模型测试研究

本文讨论大型线性方程组迭代解的随机模型测试评价问题。给出了常用迭代解法ＣＧ、ＬＳＱＲ、ＳＩＲＴ、ＳＡＲＴ、ＳＡＳＩＲＴ等的测试结果。结果表明：（１）方程组系数矩阵的特性（条件数）及解结构都对解精度有重要影响。解模型越粗糙，解的精度越低。（２）各种求解算法都有一定的平滑效应，同时各种算法也都会产生误差大于２００％的奇异解，奇异解元素数一般约占１０％。（３）数据的拟合残差一般不能真实反映解的精度。（４）对含误差数据的求解问题，较好的求解算法是ＤＬＳＱＲ与ＳＡＳＩＲＴ。

基于物理模型的成像算法评价与 SASART 成像算法

基于物理模型的图像重建算法评价方法，作者研究设计的ＳＡＳＡＲＴ算法，给出了常用算法ＳＶＤ，ＣＧ，ＬＳＱＲ，阻尼ＬＳＱＲ，ＳＩＲＴ，ＳＡＲＴ及ＳＡＳＡＲＴ的测试结果。测试数据表明：（１）线性成像方程系统的特性（条件数）及解结构都对解精度有影响，解模型越粗糙，解的精度越低；（２）自激励联合迭代重建算法（ＳＡＳＡＲＴ）迭代稳定、抗噪音能力强，用于高噪数据反演能获得合理的图像；（３）各种求解算法都具有平滑效应，同时也都会产生误差很大（＞１５０％）的奇异解；（４）小的数据拟合差并不一定指示解的精度高；（５）对含误差数据，应用阻尼ＬＳＱＲ或ＳＡＳＡＲＴ算法进行成像反演。

关于中国剩余定理

给出了主理想整环上线性同余方程组有解的充要条件,以及求解这类方程组的一个简便算法.