### Overview

The aim of this package is to show a possible implementation of perturbation
methods in *Mathematica*. It can be used to generate educational examples
of perturbation expansions.

The current version of the package covers asymptotic expansions of the solutions
of ordinary differential equations (ODE's) with respect to polynomial or general
gauge functions (according to the main sources of literature cited above). The
methods of straightforward expansions, strained coordinates and matched and
composite solutions are implemented.

The method of strained coordinates only uses the simple scheme of
Linstedt-PoincarŽ.

The matching scheme used for matched and composite expansions equals the n-th
order asymptotic expansion of the inner solution of order n (transformed to
outer coordinates) to the n-th order asymptotic expansion of the outer solution
of order n (transformed to inner coordinates).