All floating point values in femm are stored in double precision. It wouldn't be that hard to change things to use more precision, but double has seemed to be adequate before.
Diamagnetic and paramagnetic effects are difficult to measure
experimentally and are just as difficult to model. I would concur with
Dave, that a very fine mesh would be required and it may be that FEMM
doesn't work to sufficient significant figures to deal with the problem.
What precision do you use Dave?
Keith.