# discretize.TreeMesh.project_edge_to_boundary_edge#

TreeMesh.project_edge_to_boundary_edge#

Projection matrix from all edges to boundary edges.

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

ub = P @ u

Returns
(n_boundary_edges, n_edges) scipy.sparse.csr_matrix

Projection matrix with shape