Converting amplitudes between polarization models

[nkhusid]

For the aligned polarization model, the A parameter is different from that of the generic model; when enforcing equatorial plane symmetry (the aligned model), the angular factors $\enspace_{-2}Y_{\ell m} \enspace$ are factored out of the mode amplitudes, whereas no constraints on polarizations (the generic model) allows us to absorb the angular factors into the intrinsic mode amplitudes. I have written a method in result.py called get_generic_amplitude() which converts the A outputted by the aligned model into that of the generic model.

[maxisi]

great! a few requests:

1. shouldn't this just return a if the generic model was used rather than failing?
2. the mode object has a get_coordinate() method which is what you should use to get the byte string that indexes the mode in the arViz file (you should not build the bytes manually, because we might change how the indexing is done and then your code would break --- but get_coordinate will always work)

[Copilot]

Pull Request Overview

This PR introduces a new method, get_generic_amplitude(), in result.py to convert amplitudes from the aligned model to those of the generic model by integrating the angular factors.

• Added get_generic_amplitude() method
• Converts aligned model "A" values to generic model amplitudes by computing angular factors
• Validates input by checking for the existence of the "cosi" key in the posterior data

Comments suppressed due to low confidence (1)

ringdown/result.py:976

• Consider adding a docstring for get_generic_amplitude() to describe its purpose, input expectations, and returned output for future maintainability.

def get_generic_amplitude(self):

[Copilot]

Ensure that the shapes of ylm_p, ylm_m, and C are consistent for element-wise multiplication to avoid broadcasting issues; consider asserting or documenting the expected dimensions.

Suggested change

	ylm_m = swsh(-cosi)
	ylm_m = swsh(-cosi)
	# Assert shape consistency
	assert C.shape == ylm_p.shape == ylm_m.shape, (
	f"Shape mismatch: C.shape={C.shape}, ylm_p.shape={ylm_p.shape}, ylm_m.shape={ylm_m.shape}"
	)