test_units.py 文件源码

def test_power():
    """
    Take units to some power.

    """
    from sympy import nsimplify

    pc_cgs = cm_per_pc
    mK_cgs = 1e-3
    u1_dims = mass * length**2 * time**-3 * temperature**4
    u1 = Unit("g * pc**2 * s**-3 * mK**4")

    u2 = u1**2

    assert_true(u2.dimensions == u1_dims**2)
    assert_allclose_units(u2.base_value, (pc_cgs**2 * mK_cgs**4)**2, 1e-12)

    u3 = u1**(-1.0/3)

    assert_true(u3.dimensions == nsimplify(u1_dims**(-1.0/3)))
    assert_allclose_units(u3.base_value, (pc_cgs**2 * mK_cgs**4)**(-1.0/3), 1e-12)