Scattering angle for reflectometry #528
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| @pytest.mark.parametrize('polar', [np.pi / 3, np.pi / 2, 2 * np.pi / 3, np.pi]) | ||
| def test_scattering_angle_in_yz_plane_reproduces_angles_azimuth_greater_pi( |
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I may be wrong but it looks to me like this test is doing exactly the same as the previous test? Is it that the values in the parametrize should be different?
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You are right. This was copied from a test for the regular scattering angles that includes the azimuthal angle. But I removed that angle...
| y += sc.dot(scattered_beam, ey).to(dtype=elem_dtype(wavelength), copy=False) | ||
| y = sc.abs(y, out=y) | ||
| z = sc.dot(scattered_beam, ez).to(dtype=elem_dtype(y), copy=False) | ||
| return sc.atan2(y=y, x=z, out=y) |
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Looks good but same question as before: have you checked that it gives the same results as before?
I guess we also expect a difference because we used asin in the reflectometry code, but if we replace that by an atan we should get identical results?
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It does not give the same results because of the sign error in the old code. I did not see any difference from the asin / atan change. But I am still investigating.
First step for scipp/essreflectometry#54
This computes$\gamma$ as defined in https://doi.org/10.1016/j.nima.2016.03.007. ESSreflectometry will subtract $\omega$ to obtain $\theta$ because, this way,
scattering_angle_in_yz_planeis more generic.