def test_double_index(subset_func, subset_func2):
    adata = gen_adata((10, 10))
    obs_subset = subset_func(adata.obs_names)
    var_subset = subset_func2(adata.var_names)
    v1 = adata[obs_subset, var_subset]
    v2 = adata[obs_subset, :][:, var_subset]

    assert np.all(asarray(v1.X) == asarray(v2.X))
    assert np.all(v1.obs == v2.obs)
    assert np.all(v1.var == v2.var)
def test_lens_makers_formula():
    n1, n2 = symbols('n1, n2')
    m1 = Medium('m1', permittivity=e0, n=1)
    m2 = Medium('m2', permittivity=e0, n=1.33)
    assert lens_makers_formula(n1, n2, 10, -10) == 5*n2/(n1 - n2)
    assert ae(lens_makers_formula(m1, m2, 10, -10), -20.15, 2)
    assert ae(lens_makers_formula(1.33, 1, 10, -10),  15.15, 2)