一类非线性方程组的Newton-PSS迭代法

正定反Hermite分裂(PSS)方法是求解大型稀疏非Hermite正定线性代数方程组的一类无条件收敛的迭代算法.将其作为不精确Newton方法的内迭代求解器,我们构造了一类用于求解大型稀疏且具有非Hermite正定Jacobi矩阵的非线性方程组的不精确Newton-PSS方法,并对方法的局部收敛性和半局部收敛性进行了详细的分析.数值结果验证了该方法的可行性与有效性.     

松驰型并行多分裂方法解非线性方程组的安全界

本文对某些非线性方程组Ｆ（ｘ）＝０，导出了一个算法，用它可以迭代建立Ｆ（ｘ）＝０的解的紧致上、上界。算法基于某些矩阵的多分裂，因此具有自然的并行性。我们证明了趋于解的界之收敛原则，给出了参数的收敛性区域并考察了方法的收敛速度。     

非线性方程组的具有单边初值条件的分裂型单调迭代数

本文利用区间迭代法的思想，提出一种使用单边初值条件的分裂型单调迭代方法，证明了该方法的收敛性，并且具体化到常见的单调迭代法。     

解非线性方程组的一类算法

§1.引言 求解线性方程组 a_i~Tx=b_i,i=1,2,…,n,(1.1)其中a_1,a_2,…,a_n线性无关. 设y~((1))为初值,U~((1))为任意非奇异n阶矩阵,我们用如下方法求解方程组(1.1). 先考虑前k-1个方程组成的亚定方程组 a_i~Tx=b_i,i=1,2,…,k-1.设{U~((k))}={a_1,a_2,…,a_(k-1)},这里{U~((k))}表示由U~((k))的列组成的子空间.显然,rank(U~((k)))=n-b+1.若y~((k))是相应的亚定方程的一个特解,则将其看作方程组     

松弛型并行多分裂方法解非线性方程组的安全界

本文对某些非线性方程组F(x)=0,导出了一个算法,用它可以迭代建立F(x)=0的解的紧致上、下界。算法基于某些矩阵的多分裂,因此具有自然的并行性。我们证明了趋向于解的界之收敛原则,给出了参数的收敛性区域并考察了方法的收敛速度。     

求解非线性方程组的L-M方法

本文研究了求解奇异非线性方程组的Levenberg-Marquardt方法的收敛性.利用选取新的迭代参数求解非线性方程组的L-M方法,获得点列的超线性收敛性和二阶收敛性,并把试验结果与文献[19,20]的结果进行了比较.     

非线性绝对值方程组的类SOR迭代方法

提出了非线性绝对值方程组(AVE)问题解的存在性和唯一性的一个充分条件,构建了数值求解方程组的类超松弛迭代方法,并证明其收敛性.数值算例表明该迭代方法是非常有效的.     

一类非线性二阶椭圆型方程组的正解

本文讨论二阶非线性椭圆边值问题的正解的存在性,其中非线性项f和g关于u,v的增长限制很不相同.f是超线性的,而g满足次线性的条件.利用拓扑度理论和上、下解方法,得到了几个正解的存在性定理.作为应用,本文还给出了一些具体的例子.     

ON NEWTON-HSS METHODS FOR SYSTEMS OF NONLINEAR EQUATIONS WITH POSITIVE-DEFINITE JACOBIAN MATRICES

The Hermitian and skew-Hermitian splitting （HSS） method is an unconditionally convergent iteration method for solving large sparse non-Hermitian positive definite system of linear equations. By making use of the HSS iteration as the inner solver for the Newton method, we establish a class of Newton-HSS methods for solving large sparse systems of nonlinear equations with positive definite Jacobian matrices at the solution points. For this class of inexact Newton methods, two types of local convergence theorems are proved under proper conditions, and numerical results are given to examine their feasibility and effectiveness. In addition, the advantages of the Newton-HSS methods over the Newton-USOR, the Newton-GMRES and the Newton-GCG methods are shown through solving systems of nonlinear equations arising from the finite difference discretization of a two-dimensional convection-diffusion equation perturbed by a nonlinear term. The numerical implemen- tations also show that as preconditioners for the Newton-GMRES and the Newton-GCG methods the HSS iteration outperforms the USOR iteration in both computing time and iteration step.     

ON MONOTONE CONVERGENCE OF NONLINEARMULTISPLITTING RELAXATION METHODS

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A CLASS OF DECOMPOSITION METHODS FOR LARGE-SCALE SYSTEMS OF NONLINEAR EQUATIONS

This paper presents a new decomposition method for solving large-scale systems of nonlinear equations. The new method is of superlinear convergence speed and has rather less computa tional complexity than the Newton-type decomposition method as well as other known numerical methods, Primal numerical experiments show the superiority of the new method to the others.     

STABILITY ANALYSIS OF RUNGE-KUTTA METHODS FOR NONLINEAR SYSTEMS OF PANTOGRAPH EQUATIONS

This paper is concerned with numerical stability of nonlinear systems of pantograph equations. Numerical methods based on （k, l）-algebraically stable Runge-Kutta methods are suggested. Global and asymptotic stability conditions for the presented methods are derived.     

三步五阶迭代方法解非线性方程组

本文根据求积公式, 给出了三种求解非线性方程组的迭代方法, 并证明了所提出的三步迭代方法具有五阶收敛性. 最后给出了四个数值实例, 将本文的实验结果与现有的几种迭代方法的实验结果作了比较分析, 表明本文所提出的方法具有明显的优越性.     

Skew-Hermitian Triangular Splitting Iteration Methods for Non-Hermitian Positive Definite Linear Systems of Strong Skew-Hermitian Parts

By further generalizing the skew-symmetric triangular splitting iteration method studied by Krukier, Chikina and Belokon (Applied Numerical Mathematics, 41 (2002), pp. 89–105), in this paper, we present a new iteration scheme, called the modified skew-Hermitian triangular splitting iteration method, for solving the strongly non-Hermitian systems of linear equations with positive definite coefficient matrices. We discuss the convergence property and the optimal parameters of this new method in depth. Moreover, when it is applied to precondition the Krylov subspace methods like GMRES, the preconditioning property of the modified skew-Hermitian triangular splitting iteration is analyzed in detail. Numerical results show that, as both solver and preconditioner, the modified skew-Hermitian triangular splitting iteration method is very effective for solving large sparse positive definite systems of linear equations of strong skew-Hermitian parts.     

关于非Hermitian正定线性代数方程组的超松弛HSS方法

本文针对求解大型稀疏非Hermitian正定线性方程组的HSS迭代方法,利用迭代法的松弛技术进行加速,提出了一种具有三个参数的超松弛HSS方法(SAHSS)和不精确的SAHSS方法(ISAHSS),它采用CG和一些Krylov子空间方法作为其内部过程,并研究了SAHSS和ISAHSS方法的收敛性.数值例子验证了新方法的有效性.     

POSITIVE SOLUTIONS FOR WEAKLY COUPLED NONLINEAR ELLIPTIC SYSTEMS

In this article,we consider the existence of positive solutions for weakly cou-pled nonlinear elliptic systems {-△u+u (1+a(x))|u| p-1 u+μ|u| α-2 u|v|β+λv in R~N,-△v+v=(1+bx))|v|p-1v+μ|u|α|v|β-2v+λu in R N.(0.1) To find nontrivial solutions,we first investigate autonomous systems.In this case,results of bifurcation from semi-trivial solutions are obtained by the implicit function theorem.Next,the existence of positive solutions of problem(0.1) is obtained by variational methods.