Creates a symmetry operation from a rotation matrix and a translation
        vector.

        Args:
            rotation_matrix (3x3 array): Rotation matrix.
            translation_vec (3x1 array): Translation vector.
            tol (float): Tolerance to determine if rotation matrix is valid.

        Returns:
            SymmOp object

def from_rotation_and_translation(
            rotation_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)),
            translation_vec=(0, 0, 0), tol=0.1):
        """
        Creates a symmetry operation from a rotation matrix and a translation
        vector.

        Args:
            rotation_matrix (3x3 array): Rotation matrix.
            translation_vec (3x1 array): Translation vector.
            tol (float): Tolerance to determine if rotation matrix is valid.

        Returns:
            SymmOp object
        """
        rotation_matrix = np.array(rotation_matrix)
        translation_vec = np.array(translation_vec)
        if rotation_matrix.shape != (3, 3):
            raise ValueError("Rotation Matrix must be a 3x3 numpy array.")
        if translation_vec.shape != (3,):
            raise ValueError("Translation vector must be a rank 1 numpy array "
                             "with 3 elements.")
        affine_matrix = np.eye(4)
        affine_matrix[0:3][:, 0:3] = rotation_matrix
        affine_matrix[0:3][:, 3] = translation_vec
        return SymmOp(affine_matrix, tol)