TITLE:
Computational methods in perturbation theory

AUTHOR:
Angel Jorba
Departament de Matematiques i Informatica
Universitat de Barcelona, Gran Via 585, 08007 Barcelona, Spain

E-mail: angel@maia.ub.es

ABSTRACT:
The equations of motion of many physical systems can be written as the
sum of two parts, a first part that is solvable by closed formulas and
a second one which is small. Perturbation theory encloses a set of
methods to find approximate solutions that are written as a solution
of the solvable part plus small corrections coming from the small
part. Numerical methods in perturbation theory comprises numerical
techniques that compute approximate solutions by taking advantage of
the perturbative situation.

This is a contribution to the "Encyclopedia of Complexity and Systems
Science".