The specification of the large magnets needed in future fusion reactor
s based on the tokamak concept is presented as an inverse electromagne
tic problem. The influence of the eddy currents flowing in the metalli
c structure is illustrated. Currently used computational tools and rel
ated mathematical formulations are reviewed. The behavior predicted by
the numerical models is in agreement with experimental measurements,
as demonstrated by a campaign of code validation. Recent progress on t
he techniques for the identification of the plasma parameters and for
the scenario optimization is presented.