numpy.dot(B, P)

    See also :func:`reconstruct_matrix_from_id` and
    :func:`reconstruct_skel_matrix`.

    ..  This function automatically detects the matrix data type and calls the
        appropriate backend. For details, see :func:`_backend.idd_reconint` and
        :func:`_backend.idz_reconint`.

    Parameters
    ----------
    idx : :class:`numpy.ndarray`
        Column index array.
    proj : :class:`numpy.ndarray`
        Interpolation coefficients.

    Returns
    -------
    :class:`numpy.ndarray`
        Interpolation matrix.
    r