Richardson extrapolation in boundary value problems for differential equations with nonregular right-hand side

When the finite-difference method is used to solve initial- or boundary value problems with smooth data functions, the accuracy of the numerical results may be considerably improved by acceleration techniques like Richardson extrapolation. However, the success of such a technique is doubtful in cases were the right-hand side or the coefficients of the equation are not sufficiently smooth, because the validity of an asymptotic error expansion — which is the theoretical prerequisite for the convergence analysis of the Richardson extrapolation — is not a priori obvious. In this work we show that the Richardson extrapolation may be successfully applied to the finite-difference solutions of boundary value problems for ordinary second-order linear differential equations with a nonregular right-hand side. We present some numerical results confirming our conclusions.     

Non polynomial splines and weakly singular two-point boundary value problems

In the present paper we shall consider an application of simple non-polynomial splines to a numerical solution of a weakly singular two-point boundary value problem:x ^– (x y)=f(x,y), (0<x1) subject toy(0)=0,y(1)=c ₁(1) ory(0)=c ₂,y(1)=c ₃(0<<1). Our collocation method gives a continuously differentiable approximation and isO(h ²)-convergent.     

Numerical solution of singular boundary value problems via Chebyshev polynomial and B-spline

In this paper, we present B-spline method for numerically solving singular two-point boundary value problems for certain ordinary differential equation having singular coefficients.These problems arise when reducing partial differential equation to ordinary differential equation by physical symmetry. To remove the singularity, we first use Chebyshev economizition in the vicinity of the singular point and the boundary condition at a point x=δ (in the vicinity of the singularity) is derived. The resulting regular BVP is then efficiently treated by employing B-spline for finding the numerical solution. Some examples have been included and comparison of the numerical results made with other methods.     

A class of singular perturbed problems with nonlinear boundary value conditions for higher order equations

研究了一类非线性高阶微分方程的奇摄动问题.运用合成展开法构造了问题的形式渐进解,并运用了微分不等式理论证明了原问题解的存在性及所得形式渐近解的一致有效性,最后给出了一个例子说明结果的意义.     

一类具非线性边界条件的高阶方程的奇摄动问题

通过引入伸展变量和非常规的渐近序列{∈}）,运用合成展开法,对一类具非线性边界条件的非线性高阶微分方程的奇摄动问题构造了形式渐近解,再运用微分不等式理论证明了原问题解的存在性及所得渐近近似式的一致有效性．     

Singularly perturbed boundary value problems

1.IntroductionThesingularlypedurbednonlineartwO-pointboundaryvalueproblemsinthisarticleareofthefollowingtypewhereconstantparametere>0,constantsx?ER,asERe.Thestatesofthesystem(XI(t),Xz(t),YI(t),YZ(t)),whichtakevaluesinRxRexRadxRe,containonepart(XI(t),YI(t))calledslowvariablesandonepart(XZ(t),YZ(t))calledfastvariables.Welookforthesolutions(XI,X2,YI,Y2)EL'(0,T;R m m)whichsatisfysystem(1).Suchasituationiscommonintheapplications.Itappearsforexampleineconomicmodelstotakeintoaccoun…     

Positive solutions for nonlinear singular boundary value problems

Some sufficient conditions for the existence of positive solutions to Dirichlet boundary value problems of a class of nonlinear second order differential equations are given.     

Positive solutions for singular semi-positone boundary value problems

In this paper, some new results about the existence of positive solutions for singular semi-positone boundary value problems are obtained. The results of this paper partially improve the former corresponding work.     

一类具非线性边界条件的高阶方程的双参数奇摄动问题

研究了一类含双参数的非线性高阶微分方程的奇摄动问题.运用合成展开法构造了问题的形式渐近解,并运用微分不等式理论证明了原问题解的存在性及所得形式渐近解的一致有效性.     

Uniqueness and existence for perturbed focal boundary value problems

Assuming a uniqueness assumption on the variational boundary value problems, uniqueness and existence is established for problems which generalize focal boundary value problems.     

Boundary integral methods for singularly perturbed boundary value problems

In this paper we consider boundary integral methods appliedto boundary value problems for the positive definite Helmholtz-typeproblem –U + ²U = 0 in a bounded or unbounded domain,with the parameter real and possibly large. Applications arisein the implementation of space–time boundary integralmethods for the heat equation, where is proportional to 1/(t),and t is the time step. The corresponding layer potentials arisingfrom this problem depend nonlinearly on the parameter and havekernels which become highly peaked as , causing standard discretizationschemes to fail. We propose a new collocation method with arobust convergence rate as . Numerical experiments on a modelproblem verify the theoretical results.     

Global convergence method for singularly perturbed boundary value problems

We give uniformly convergent splines difference scheme for singularly perturbed boundary value problems(1)$-\epsilon u^{″}+p(x)u^{\prime }+q(x)u=f(x),u(a)={\alpha }_0,u(b)={\alpha }_1,$by using splines fitted with delta sequence due to the very stiff nature of the problem under consideration. We prove the $\mathrm{O}(\min (h^2,{\epsilon }^2))$ order of uniform convergence with respect to small parameter $\epsilon$ at nodes on uniform mesh and $\mathrm{O}(\min (h,\epsilon ))$ order of uniform global convergence with respect to the approximate solution given by $S(x)={\sum }_{i=1}^N{S}_{{\Delta }_i}(x)H(x_i-x)$ where H is the Heaviside function, which is the approximation for the closed form of the exact solution.     

On singular partial differential boundary problems

Summary In the first part, the existence of a differential operator is established that is elliptic inside a domain and singular on the boundary. In the second part the invariance of the essential spectrum is established under a large class of perturbations of the original boundary problem. To Giovanni Sansone on his 70^th birthday. This research has partially been supported by a grant of the United States National Science Foundation.     

奇摄动非线性边值问题

The singularly perturbed nonlinear boundary value problems are considered. Using the stretched variable and the method of boundary layer correction,the formal asymptotic expansion of solution is obtained. And then the uniform validity of solution is proved by using the differential inequalities.     

Singularly perturbed boundary value problems with a power-law boundary layer

We consider boundary value problems for second-order singularly perturbed equations whose solution has a power-law boundary layer that occurs because the degenerate equation has multiple roots.     

Existence of solutions for nonlinear singular boundary value problems

Existence of solutions to the two-point boundary value problem (p(t)y')' = q(t)f(t, y,p(t)y'), y(l) = 0, lim_t→0+ p(t)y'(t) = 0 is established under a variety of conditions. Here p(0) = 0 is allowed, and q is not assumed to be continuous at 0, so the problem may be doubly singular. In addition, the Dirichlet problem for this differential equation is investigated     

Initial-value technique for self-adjoint singular perturbation boundary value problems

We have developed an initial-value technique for self-adjoint singularly perturbed two-point boundary value problems. The original problem is reduced to its normal form, and the reduced problem is converted into first-order initial-value problems. These initial-value problems are solved by the cubic spline method. Numerical illustrations are given at the end to demonstrate the efficiency of our method. Graphs are also depicted in support of the results. An erratum to this article can be found at     

Modified hierarchy basis for solving singular boundary value problems

In this paper, we develop an efficient preconditioning method on the basis of the modified hierarchy basis for solving the singular boundary value problem by the Galerkin method. After applying the preconditioning method, we show that the condition number of the linear system arising from the Galerkin method is uniformly bounded. In particular, the condition number of the preconditioned system will be bounded by 2 for the case q(x)=0 (see Eq. (1) in the paper). Numerical results are presented to confirm our theoretical results.