def test_curl_free_current_magnitudes():
"Make sure the curl free current amplitudes are correct."
# Place the SEC at the North Pole
sec_r = R_EARTH + 100
sec_latlonr = np.array([[0., 0., sec_r]])
# Going out in an angle from the SEC (in longitude)
angles = np.linspace(0.1, 180)
obs_latlonr = np.zeros(angles.shape + (3, ))
obs_latlonr[:, 1] = angles
obs_latlonr[:, 2] = sec_r
J = np.squeeze(pysecs.J_cf(obs_latlonr, sec_latlonr))
# Make sure all radial components are oppositely directed
radial_component = 1. / (4 * np.pi * sec_r**2)
assert np.all(J[:, 2] == radial_component)
# All x components should be zero (angles goes around the equator and all
# quantities should be parallel to that)
# (ambiguous 0 degree angle so ignore the first input)
assert_allclose(np.zeros(angles.shape), J[:, 0], atol=1e-16)
# Actual magnitude
tan_theta2 = np.tan(np.deg2rad(angles / 2))
J_test = 1. / (4 * np.pi * sec_r)
J_test = np.divide(J_test,
tan_theta2,
out=np.ones_like(tan_theta2) * np.inf,
where=tan_theta2 != 0.)
assert_allclose(J_test, J[:, 1], atol=1e-16)
def test_outside_current_plane():
"Make sure all currents outside the SEC plane are 0."
sec_r = R_EARTH + 100
sec_latlonr = np.array([[0., 0., sec_r]])
# Above and below the plane, also on and off the SEC point
obs_latlonr = np.array([[0., 0., sec_r - 100.], [0., 0., sec_r + 100.],
[5, 0., sec_r - 100.], [5., 0., sec_r + 100.]])
# df currents
J = np.squeeze(pysecs.J_df(obs_latlonr, sec_latlonr))
assert np.all(J == 0.)
# cf currents
J = np.squeeze(pysecs.J_cf(obs_latlonr, sec_latlonr))
assert np.all(J == 0.)
def test_curl_free_current_directions():
"Make sure the curl free current angles are correct."
# Place the SEC at the equator
sec_r = R_EARTH + 100
sec_latlonr = np.array([[0., 0., sec_r]])
# Going around in a circle from the point
obs_latlonr = np.array([[5., 0., sec_r], [0., 5., sec_r], [-5, 0., sec_r],
[0., -5., sec_r]])
J = np.squeeze(pysecs.J_cf(obs_latlonr, sec_latlonr))
angles = np.arctan2(J[:, 0], J[:, 1])
# pointing out from the SEC direction to OBS direction.
# northward, eastward, southward, westward
expected_angles = np.deg2rad([90., 0., -90., -180])
assert_allclose(angles, expected_angles, atol=1e-15)