Solving ordinary differential equations on the Infinity Computer by working with infinitesimals numerically

TL;DR

This paper introduces a novel computational framework using the Infinity Computer, capable of numerically handling infinitesimals to solve ODEs more efficiently by calculating derivatives and Taylor expansions without symbolic derivation.

Contribution

It presents a new numerical approach for solving ODEs using the Infinity Computer's ability to work with infinitesimals, enabling derivative calculation and Taylor expansion without symbolic methods.

Findings

The Infinity Computer can numerically compute derivatives of solutions.

The framework allows for automatic rounding error control.

Numerical examples demonstrate the method's effectiveness.

Abstract

There exists a huge number of numerical methods that iteratively construct approximations to the solution $y(x)$ of an ordinary differential equation (ODE) $y'(x)=f(x,y)$ starting from an initial value $y_0=y(x_0)$ and using a finite approximation step $h$ that influences the accuracy of the obtained approximation. In this paper, a new framework for solving ODEs is presented for a new kind of a computer -- the Infinity Computer (it has been patented and its working prototype exists). The new computer is able to work numerically with finite, infinite, and infinitesimal numbers giving so the possibility to use different infinitesimals numerically and, in particular, to take advantage of infinitesimal values of $h$. To show the potential of the new framework a number of results is established. It is proved that the Infinity Computer is able to calculate derivatives of the solution $y(x)$ and to reconstruct its Taylor expansion of a desired order numerically without finding the respective derivatives analytically (or symbolically) by the successive derivation of the ODE as it is usually done when the Taylor method is applied. Methods using approximations of derivatives obtained thanks to infinitesimals are discussed and a technique for an automatic control of rounding errors is introduced. Numerical examples are given.