def mat44_from_mat33(mat33):
    """
    Creates a 4x4 matrix from given 3x3 matrix.

    Parameters
    ----------
    mat33 : array of float
        A 3x3 matrix

    Returns
    -------
    array of float
         A 4x4 matrix
    """

    return [mat33[0], mat33[1], mat33[2], 0,
            mat33[3], mat33[4], mat33[5], 0,
            mat33[6], mat33[7], mat33[8], 0,
            0, 0, 0, 1]