Multiple scales and matched asymptotic expansions for the discrete logistic equation

TL;DR

This paper develops a combined asymptotic method using multiple scales and matched expansions to analyze difference equations near period-doubling bifurcations, providing a general strategy for singularly-perturbed problems.

Contribution

It introduces a novel combined approach for asymptotic solutions of difference equations, addressing late-time behavior and singular perturbations.

Findings

Successfully constructs uniform asymptotic solutions near bifurcations.

Provides a general strategy applicable to singularly-perturbed difference equations.

Identifies indicators for choosing between multiple scales and matched asymptotic methods.

Abstract

In this paper, we combine the method of multiple scales and the method of matched asymptotic expansions to construct uniformly-valid asymptotic solutions to autonomous and non-autonomous difference equations in the neighbourhood of a period-doubling bifurcation. In each case, we begin by constructing multiple scales approximations in which the slow time scale is treated as a continuum variable, leading to difference-differential equations. The resultant approximations fail to be asymptotic at late time, due to behaviour on the slow time scale, it is necessary to eliminate the effects of the fast time scale in order to find the late time rescaling, but there are then no difficulties with applying the method of matched asymptotic expansions. The methods that we develop lead to a general strategy for obtaining asymptotic solutions to singularly-perturbed difference equations, and we discuss clear indicators of when multiple scales, matched asymptotic expansions, or a combined approach might be appropriate.