sot/eng_archive — comment on commit 1acd02e48303b6ea6229a62e120a7d02f0c54f9f
File: Ska/engarchive/derived/pcad.py line 172
By taldcroft:

I think (?) you can just do:

q3 = np.abs(delta_quat_norm[3, :])
man_ang = 2 * np.degrees(np.arccos(q3))

and then skip the whole `over180` business. This is related to the fact that you can multiply all components of a quaternion by -1 without changing anything. If `q3` is then positive you are sure to get an angle 0 <= man_ang < 180.