# discretize.CurvilinearMesh.project_face_to_boundary_face¶

property CurvilinearMesh.project_face_to_boundary_face

Projection matrix from all faces to boundary faces.

Constructs and returns a matrix $$\mathbf{P}$$ that projects from all mesh faces to boundary faces. That is, for a discrete vector $$\mathbf{u}$$ that lives on the faces, the values on the boundary faces $$\mathbf{u_b}$$ can be extracted via the following matrix-vector product:

ub = P @ u

Returns
scipy.sparse.csr_matrix

(n_boundary_faces, n_faces) Projection matrix with shape