Before even bothering to download....Equation Settings input panel shown at

https://www.featool.com/doc/physics#phys_msdoesn't give me a real clue as to how it could handle non scalar permeability entry.

For instance, when trying to model one or more inherently anisotropic and non-linear permeability, laminated 'electrical steel' structures, oriented arbitrarily wrt some incident B field source(s).

Could someone familiar with that kind of problem point me to if possible a worked example, or failing that the hopefully readily enterable general form for a permeability tensor array expressions incorporating said non-uniformities.

A concrete example of something roughly analogous, say permittivity tensor entries for anisotropic & nonlinear dielectric media in an electrostatics situation, or likewise for non-isotropic & non-linear elastic media stress/strain simulation, would probably give sufficient to be able to adapt to the magnetics case accordingly.