A few formulation of the magnetic vector potential method in 3-D multiply connected regions

Formulations using the continuous and discontinuous magnetic vector potential for 3-D eddy current calculation in both the simply and multiply connected regions are presented. The formulation using the continuous magnetic vector potential does not need cutting for the multiply-connected-region problem, but it needs the electric scalar potential. The formulation using the discontinuous magnetic vector potential does not need the electric scalar potential for the simply-connected-region problem, but it needs cutting for the multiply-connected region problem, so additional computation is required. Thus the former may suite the multiply-connected-region problem, while the latter may suit the simply-connected region problem