'Compare dgbtrf  LU factorisation with the LU factorisation result
of linalg.lu.'

def test_dgbtrf(self):

    (M, N) = shape(self.real_mat)
    (lu_symm_band, ipiv, info) = dgbtrf(self.bandmat_real, self.KL, self.KU)
    u = diag(lu_symm_band[(2 * self.KL), :])
    for i in xrange((self.KL + self.KU)):
        u += diag(lu_symm_band[(((2 * self.KL) - 1) - i), (i + 1):N], (i + 1))
    (p_lin, l_lin, u_lin) = lu(self.real_mat, permute_l=0)
    assert_array_almost_equal(u, u_lin)
