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arXiv 2201.06501math.NAcs.NA
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线性半负问题的龙格-库塔法的能量定律和稳定性

On Energy Laws and Stability of Runge--Kutta Methods for Linear Seminegative Problems

Zheng Sun, Yuanzhe Wei, Kailiang Wu

摘要:

本文给出了一个系统的理论框架来推导线性半负方程组的一般隐式和显式Runge-Kutta(RK)方法的能量恒等式。推广了[Z. Sun和C.- W. Shu,SIAM J. Numer.肛门,57(2019),pp. 1158-1182]。所建立的能量恒等式提供了关于RK离散化中能量是否以及如何耗散的精确表征,从而导致RK方法的弱稳定性和强稳定性准则。此外,基于一类对称矩阵的解析Cholesky型分解,我们发现了所有对角Pade逼近的统一能量恒等式.矩阵的结构非常复杂,使得发现统一的能量恒等式和证明分解具有很大的挑战性。我们的证明涉及到技术的组合恒等式的建设和新的技术,从理论的超几何级数。我们的框架是由离散模拟的分部积分法技术和连续能量法的一系列扩展。在某些特殊情况下,我们的分析建立了连续和离散能量定律之间的密切联系,增强了我们对其内在机制的理解。给出了几个具体的隐式方法的例子来说明离散能量定律。一些数值例子进一步证实了理论性质。

英文摘要:

This paper presents a systematic theoretical framework to derive the energy identities of general implicit and explicit Runge--Kutta (RK) methods for linear seminegative systems. It generalizes the stability analysis of explicit RK methods in [Z. Sun and C.-W. Shu, SIAM J. Numer. Anal., 57 (2019), pp. 1158-1182]. The established energy identities provide a precise characterization on whether and how the energy dissipates in the RK discretization, thereby leading to weak and strong stability criteria of RK methods. Furthermore, we discover a unified energy identity for all the diagonal Pade approximations, based on an analytical Cholesky type decomposition of a class of symmetric matrices. The structure of the matrices is very complicated, rendering the discovery of the unified energy identity and the proof of the decomposition highly challenging. Our proofs involve the construction of technical combinatorial identities and novel techniques from the theory of hypergeometric series. Our framework is motivated by a discrete analogue of integration by parts technique and a series expansion of the continuous energy law. In some special cases, our analyses establish a close connection between the continuous and discrete energy laws, enhancing our understanding of their intrinsic mechanisms. Several specific examples of implicit methods are given to illustrate the discrete energy laws. A few numerical examples further confirm the theoretical properties.

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