# SimPEG.maps.InjectActiveCells.inverse#

InjectActiveCells.inverse(u)[source]#

Recover the model parameters (active cells) from a set of physical property values defined on the entire mesh.

For a discrete set of model parameters $$\mathbf{m}$$ defined on a set of active cells, the mapping $$\mathbf{u}(\mathbf{m})$$ is defined as:

$\mathbf{u}(\mathbf{m}) = \mathbf{Pm} + \mathbf{d} \,m_\perp$

where $$\mathbf{P}$$ is a (nC , nP) projection matrix from active cells to all mesh cells, and $$\mathbf{d}$$ is a (nC , 1) matrix that projects the inactive cell value $$m_\perp$$ to all inactive mesh cells.

The inverse mapping is given by:

$\mathbf{m}(\mathbf{u}) = \mathbf{P^T u}$
Parameters
u(mesh.nC) numpy.ndarray

A vector which contains physical property values for all mesh cells.