linear_transfer.py 文件源码

def __get_prolongation_matrix(ndofs_coarse, ndofs_fine):
        """Helper routine for the prolongation operator

        Args:
            ndofs_fine (int): number of DOFs on the fine grid
            ndofs_coarse (int): number of DOFs on the coarse grid

        Returns:
            scipy.sparse.csc_matrix: sparse prolongation matrix of size
                `ndofs_fine` x `ndofs_coarse`
        """

        # This is a workaround, since I am not aware of a suitable way to do
        # this directly with sparse matrices.
        P = np.zeros((ndofs_fine, ndofs_coarse))
        np.fill_diagonal(P[1::2, :], 1)
        np.fill_diagonal(P[0::2, :], 1.0/2.0)
        np.fill_diagonal(P[2::2, :], 1.0/2.0)
        return sp.csc_matrix(P)