The discrete Prufer transformation

The classical Prufer transformation has proved to be a useful tool in the s tudy of Sturm-Liouville theory. In this paper we introduce the Prufer trans formation for self-adjoint difference equations and use it to obtain oscill ation criteria and other results. We then offer an extension of this approa ch to the case of general symplectic systems on time scales. Time scales ha ve been introduced in order to unify discrete and continuous analysis, and indeed our results cover as special cases both the Prufer transformation fo r differential and for difference equations.