I. Introduction
Exploiting symmetry has been recognized as an effective method to save a sensible amount of simulation time. It allows to solve the problem on a given domain by solving a family of problems on a symmetry cell instead. It is impossible to survey all the literature, so we just mention [1] for the finite element method (FEM) and [2] for a FEM–boundary element method (FEM–BEM) based on the magnetic vector potential.