Differential Inversion of the Implicit Euler Method: Symbolic Analysis

Fuente: arXiv
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Autor principal: Naumann, Uwe
Formato: Preprint
Publicado: 2024
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author Naumann, Uwe
author_facet Naumann, Uwe
contents The implicit Euler method integrates systems of ordinary differential equations $$\frac{d x}{d t}=G(t,x(t))$$ with differentiable right-hand side $G : {\mathbb R} \times {\mathbb R}^n \rightarrow {\mathbb R}^n$ from an initial state $x=x(0) \in {\mathbb R}^n$ to a target time $t \in {\mathbb R}$ as $x(t)=E(t,m,x)$ using an equidistant discretization of the time interval $[0,t]$ yielding $m>0$ time steps. We present a method for efficiently computing the product of its inverse Jacobian $$(E')^{-1} \equiv \left (\frac{d E}{d x}\right )^{-1} \in {\mathbb R}^{n \times n} $$ with a given vector $v \in {\mathbb R}^n.$ We show that the differential inverse $(E')^{-1} \cdot v$ can be evaluated for given $v \in {\mathbb R}^n$ with a computational cost of $\mathcal{O}(m \cdot n^2)$ as opposed to the standard $\mathcal{O}(m \cdot n^3)$ or, naively, even $\mathcal{O}(m \cdot n^4).$ The theoretical results are supported by actual run times. A reference implementation is provided.
format Preprint
id arxiv_https___arxiv_org_abs_2409_05445
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Differential Inversion of the Implicit Euler Method: Symbolic Analysis
Naumann, Uwe
Numerical Analysis
Computational Engineering, Finance, and Science
65F05
The implicit Euler method integrates systems of ordinary differential equations $$\frac{d x}{d t}=G(t,x(t))$$ with differentiable right-hand side $G : {\mathbb R} \times {\mathbb R}^n \rightarrow {\mathbb R}^n$ from an initial state $x=x(0) \in {\mathbb R}^n$ to a target time $t \in {\mathbb R}$ as $x(t)=E(t,m,x)$ using an equidistant discretization of the time interval $[0,t]$ yielding $m>0$ time steps. We present a method for efficiently computing the product of its inverse Jacobian $$(E')^{-1} \equiv \left (\frac{d E}{d x}\right )^{-1} \in {\mathbb R}^{n \times n} $$ with a given vector $v \in {\mathbb R}^n.$ We show that the differential inverse $(E')^{-1} \cdot v$ can be evaluated for given $v \in {\mathbb R}^n$ with a computational cost of $\mathcal{O}(m \cdot n^2)$ as opposed to the standard $\mathcal{O}(m \cdot n^3)$ or, naively, even $\mathcal{O}(m \cdot n^4).$ The theoretical results are supported by actual run times. A reference implementation is provided.
title Differential Inversion of the Implicit Euler Method: Symbolic Analysis
topic Numerical Analysis
Computational Engineering, Finance, and Science
65F05
url https://arxiv.org/abs/2409.05445