# SimPEG.potential_fields.magnetics.Simulation3DDifferential.fields#

Simulation3DDifferential.fields(m)[source]#

Return magnetic potential (u) and flux (B) u: defined on the cell center [nC x 1] B: defined on the cell center [nG x 1]

After we compute u, then we update B.

$\mathbf{B}_s = (\MfMui)^{-1}\mathbf{M}^f_{\mu_0^{-1}}\mathbf{B}_0-\mathbf{B}_0 -(\MfMui)^{-1}\Div^T \mathbf{u}$