  The spatial discretization of the magnetic vector potential formulation of
magnetoquasistatic field problems results in an infinitely stiff
differential-algebraic equation system. It is transformed into a finitely stiff
ordinary differential equation system by applying a generalized Schur
complement. Applying the explicit Euler time integration scheme to this system
results in a small maximum stable time step size. Fast computations are
required in every time step to yield an acceptable overall simulation time.
Several acceleration methods are presented.
