Wim Vanroose,

Department of Mathematics and Computer Sciences.
Applied Mathematics and Numerical Analysis
University Antwerpen, Belgium

This tutorial talks about extracting the far-field-map from the numerical solution of a
Helmholtz or a Schroedinger problem solved on a finite numerical box. We try to make the
connection between imaging concepts, traditionally described by the
Helmholtz equation and the equivalent concepts in the Schroedinger equation.

In scattering calculations of atomic and molecular processes it is relatively straightforward
to obtain a high dimensional wave function describing the scattering. Extracting the cross
section of the various processes from that wave function is, in contrast, a delicate matter.

We give a tutorial in extracting the amplitudes from wave functions. We start from the
Helmholtz equation and we slowly evolve to more complicated atomic and molecular processes.