mode_sign_convention
When comparing against different cases, it is important that the modes share a common sign convention.
In this case, modes will be arranged such that the z-coordinate of the first free end is positive.
If the z-coordinate is 0, then the y-coordinate is forced to be positive, then x, followed by the CRV in y, x and z.
- returns:
Eigenvectors following the aforementioned sign convention.
- rtype:
np.ndarray