'1 set 1D x, 2 sets 1D y, 2 param_sets'

def test_linear_fitter_Nset(self):

    expected = np.array([[0, 0], [1, 1], [2, 2], [3, 3]])
    p1 = models.Polynomial1D(3, n_models=2)
    p1.parameters = [0.0, 0.0, 1.0, 1.0, 2.0, 2.0, 3.0, 3.0]
    params = {}
    for i in range(4):
        params[p1.param_names[i]] = [i, i]
    p1 = models.Polynomial1D(3, model_set_axis=0, **params)
    y1 = p1(self.x1, model_set_axis=False)
    pfit = fitting.LinearLSQFitter()
    model = pfit(p1, self.x1, y1)
    assert_allclose(model.param_sets, expected, atol=(10 ** (-7)))
