scholarly journals An error estimate for an approximate solution to ordinary differential equations obtained using the Chebyshev series

2020 ◽  
pp. 241-250
Author(s):  
О.Б. Арушанян ◽  
С.Ф. Залеткин
Keyword(s):  
Cauchy Problem ◽  
Approximate Solution ◽  
Differential Equations ◽  
Error Estimate ◽  
Ordinary Differential Equations ◽  
Chebyshev Series ◽  
Integration Interval ◽  
First Order ◽  
Partial Sum ◽  
The Cauchy Problem

Рассматривается приближенный метод решения задачи Коши для нелинейных обыкновенных дифференциальных уравнений первого порядка, основанный на применении смещенных рядов Чебышёва и квадратурной формулы Маркова. Приведены способы оценки погрешности приближенного решения, выраженного в виде частичной суммы ряда некоторого порядка. Погрешность оценивается с помощью второго приближенного решения, вычисленного специальным образом и представленного частичной суммой ряда более высокого порядка. На основе предложенных способов оценки погрешности построен алгоритм автоматического разбиения промежутка интегрирования на элементарные сегменты, делающие возможным вычисление приближенного решения с наперед заданной точностью. Работа метода проиллюстрирована примерами, в том числе примером из небесной механики. An approximate method of solving the Cauchy problem for nonlinear first-order ordinary differential equations is considered. The method is based on using the shifted Chebyshev series and a Markov quadrature formula. Some approaches are given to estimate the error of an approximate solution expressed by a partial sum of a certain order series. The error is estimated using the second approximation of the solution expressed by a partial sum of a higher order series. An algorithm of partitioning the integration interval into elementary subintervals to ensure the computation of the solution with a prescribed accuracy is discussed on the basis of the proposed approaches to error estimation.

Hodograph Method for Solving the Problem of Shallow Water Under a Solid Lid

2021 ◽  
pp. 15-24
Author(s):  
Tatiana F. Dolgikh
Keyword(s):  
Cauchy Problem ◽  
Green Function ◽  
Differential Equations ◽  
Shallow Water ◽  
Ordinary Differential Equations ◽  
Riemann Invariants ◽  
Hodograph Method ◽  
First Order ◽  
The Cauchy Problem ◽  
Derivatives Of

One of the mathematical models describing the behavior of two horizontally infinite adjoining layers of an ideal incompressible liquid under a solid cover moving at different speeds is investigated. At a large difference in the layer velocities, the Kelvin-Helmholtz instability occurs, which leads to a distortion of the interface. At the initial point in time, the interface is not necessarily flat. From a mathematical point of view, the behavior of the liquid layers is described by a system of four quasilinear equations, either hyperbolic or elliptic, in partial derivatives of the first order. Some type shallow water equations are used to construct the model. In the simple version of the model considered in this paper, in the spatially one-dimensional case, the unknowns are the boundary between the liquid layers h(x,t) and the difference in their velocities γ(x,t). The main attention is paid to the case of elliptic equations when |h|<1 and γ>1. An evolutionary Cauchy problem with arbitrary sufficiently smooth initial data is set for the system of equations. The explicit dependence of the Riemann invariants on the initial variables of the problem is indicated. To solve the Cauchy problem formulated in terms of Riemann invariants, a variant of the hodograph method based on a certain conservation law is used. This method allows us to convert a system of two quasilinear partial differential equations of the first order to a single linear partial differential equation of the second order with variable coefficients. For a linear equation, the Riemann-Green function is specified, which is used to construct a two-parameter implicit solution to the original problem. The explicit solution of the problem is constructed on the level lines (isochrons) of the implicit solution by solving a certain Cauchy problem for a system of ordinary differential equations. As a result, the original Cauchy problem in partial derivatives of the first order is transformed to the Cauchy problem for a system of ordinary differential equations, which is solved by numerical methods. Due to the bulkiness of the expression for the Riemann-Green function, some asymptotic approximation of the problem is considered, and the results of calculations, and their analysis are presented.

scholarly journals Approximate solution of the Cauchy problem for ordinary differential equations by the method of Chebyshev series

2016 ◽  
pp. 121-131
Author(s):  
О.Б. Арушанян ◽  
С.Ф. Залеткин
Keyword(s):  
Cauchy Problem ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Partial Sums ◽  
Quadrature Formulas ◽  
Chebyshev Series ◽  
Adams Methods ◽  
The Cauchy Problem ◽  
Discretization Step ◽  
Derivatives Of

Рассмотрен численно-аналитический метод решения систем обыкновенных дифференциальных уравнений, разрешенных относительно производных от искомых функций. Метод основан на приближенном представлении решения и его производной в виде частичных сумм смещенных рядов Чебышёва. Коэффициенты рядов определяются с помощью итераций с применением квадратурной формулы Маркова. Метод может быть использован для интегрирования обыкновенных дифференциальных уравнений с более высокой точностью и с более крупным шагом дискретизации по сравнению с традиционными численными методами типа Рунге-Кутта и Адамса. An approximate analytical method of solving the systems of ordinary differential equations resolved with respect to the derivatives of unknown functions is considered. This method is based on the approximation of the solution to the Cauchy problem and its derivatives by partial sums of shifted Chebyshev series. The coefficients of the series are determined by an iterative process with the use of Markov's quadrature formulas. This approach can be used to solve ordinary differential equations with a higher accuracy and with a larger discretization step compared to the known Runge-Kutta and Adams methods.

scholarly journals A numerical-analytic method for solving the Cauchy problem for ordinary differential equations

2011 ◽  
Vol 11 (4) ◽  
pp. 491-509 ◽  
Author(s):  
Volodymyr Makarov ◽  
Denys Dragunov
Keyword(s):  
Cauchy Problem ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Adomian Decomposition Method ◽  
Analytic Method ◽  
Discrete Method ◽  
First Order ◽  
Adomian Decomposition ◽  
The Cauchy Problem ◽  
Systems Of Odes

AbstractA functional-discrete method for solving the Cauchy problem for first-order ordinary differential equations (ODEs) is proposed. Generally speaking, this method (FD-method) is similar to the Adomian Decomposition Method (ADM). However, we have shown that for some problems the FD-method is convergent whereas the ADM is divergent. The results presented in this paper can easily be generalized to the case of systems of ODEs.

scholarly journals On the solvability of the modified Cauchy problem for linear systems of generalized ordinary differential equations with singularities

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Malkhaz Ashordia ◽  
Inga Gabisonia ◽  
Mzia Talakhadze
Keyword(s):  
Cauchy Problem ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Linear Systems ◽  
Unique Solvability ◽  
Sufficient Conditions ◽  
The Cauchy Problem ◽  
Generalized Ordinary Differential Equations

AbstractEffective sufficient conditions are given for the unique solvability of the Cauchy problem for linear systems of generalized ordinary differential equations with singularities.

Old and New Results for First Order Periodic ODEs without Uniqueness: a Comprehensive Study by Lower and Upper Solutions

2004 ◽  
Vol 4 (3) ◽  
Author(s):  
Franco Obersnel ◽  
Pierpaolo Omari
Keyword(s):  
Cauchy Problem ◽  
Differential Equations ◽  
Lower And Upper Solutions ◽  
Elementary Approach ◽  
Qualitative Properties ◽  
First Order ◽  
The Past ◽  
The Cauchy Problem ◽  
Qualitative Properties Of Solutions ◽  
Comprehensive Study

AbstractAn elementary approach, based on a systematic use of lower and upper solutions, is employed to detect the qualitative properties of solutions of first order scalar periodic ordinary differential equations. This study is carried out in the Carathéodory setting, avoiding any uniqueness assumption, in the future or in the past, for the Cauchy problem. Various classical and recent results are recovered and generalized.

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