simpeg.electromagnetics.time_domain.Simulation3DCurrentDensity.getAsubdiag#

Simulation3DCurrentDensity.getAsubdiag(tInd)[source]#

Sub-diagonal system matrix for the time-step index provided.

This method returns the sub-diagonal system matrix for the time-step index provided:

\[\mathbf{B}_k = -\frac{1}{\Delta t_k} \mathbf{I}\]

where \(\Delta t_k\) is the step-length and \(\mathbf{I}\) is the identity matrix.

See the Notes section of the doc strings for Simulation3DCurrentDensity for a full description of the formulation.

Parameters:
tIndint

The time-step index; between [0, n_steps-1].

Returns:
(n_faces, n_faces) sp.sparse.csr_matrix

The sub-diagonal system matrix.