M.C. Nucci and P.G.L. Leach
The essential harmony in the classical equations of mathematical physics
(73K, Latex2e)

ABSTRACT.  The possibility to transform any system of linear ordinary 
differential equations into a system of constant coefficient 
equations is demonstrated using Lie theory. Some examples relate 
the classical equations of mathematical physics to the simple 
harmonic oscillator. The r\^oles of the third order form of the 
Ermakov-Pinney equation and of Fleischen-von Weltunter systems are 
explained.