Add ability to perform simulations with per-antenna beams

[tyler-a-cox]

This PR adds the functionality to allow users provide per-antenna beams and beam_idx as matvis does. There is a slight difference between the keyword argument used to pass beams between matvis and fftvis (i.e beam in fftvis vs. beams in matvis). It may be a good idea for us to change that in the future, but for now, I left the argument as beam keep this from breaking the API.

[codecov]

Codecov Report

❌ Patch coverage is 91.83673% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.22%. Comparing base (e2a5a46) to head (f773460).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/fftvis/cpu/cpu_simulate.py	89.61%	5 Missing and 3 partials ⚠️
src/fftvis/cpu/beams.py	90.00%	1 Missing and 1 partial ⚠️
src/fftvis/wrapper.py	93.75%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
+ Coverage   93.18%   95.22%   +2.04%     
==========================================
  Files          18       18              
  Lines         484      566      +82     
  Branches       64       86      +22     
==========================================
+ Hits          451      539      +88     
+ Misses         26       17       -9     
- Partials        7       10       +3     

Flag	Coverage Δ
unittests	95.22% <91.83%> (+2.04%)	⬆️

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[Copilot]

Pull request overview

This PR adds per-antenna beam support to fftvis.simulate_vis (via a list of beams plus beam_idx) and propagates that capability through the CPU simulation engine, along with new tests covering multi-beam behavior and beam-pair flux helpers.

Changes:

• Extend the public simulate_vis wrapper to accept a single beam or a list of beams and add beam_idx.
• Update the CPU simulation engine to route baselines by beam-pair and evaluate apparent flux for mixed-beam baselines.
• Add/expand tests for multi-beam simulations and new beam-evaluation helper paths.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/fftvis/wrapper.py	Adds beam_idx, nchunks, source_buffer, and converts beam input into an internal beam_list.
src/fftvis/cpu/cpu_simulate.py	Threads beam_list/beam_idx through chunk evaluation and implements beam-pair routing logic.
src/fftvis/cpu/beams.py	Adds prepare_beam_evaluation plus cross-beam polarized apparent-flux kernels.
tests/test_wrapper.py	Adds wrapper-level validation tests for beam list / beam_idx error cases.
tests/test_cpu_simulate.py	Adds an fftvis-vs-matvis multi-beam regression test and updates calls for new arguments.
tests/test_cpu_beams.py	Adds unit tests for beam-pair routing and new polarized apparent-flux helpers.

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[steven-murray]

Thanks @tyler-a-cox -- I'm going to let you deal with Copilot's suggestions first, and then please ping me and I'll take a final look.

From my side, the code is working on bridges, so there should be nothing major to fix.

[Copilot]

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[tyler-a-cox]

@steven-murray okay, this should be good for you to review now

[steven-murray]

Thanks @tyler-a-cox., this is looking great. Thanks also for adding the option to specify the max memory. I thnk the logic that copilot added might be wrong, so maybe have another look at that, to make sure. Otherwise this is good to go.

[steven-murray]

Hmmm, this actually doesn't seem right to me. We should only include beam indices that actually exist, right? We don't need to use all pairs in the range from (0,maxidx)?

[tyler-a-cox]

I'm now building the unique beam pairs array with pairs actually used in beam_idx array

[steven-murray]

Probably the right thing to do here actually is to only ever deal with the BeamInterface (so, if UVBeam is passed to the wrapper, convert it to a BeamInterface there, so the logic throughout the rest of the code is more uniform).

[tyler-a-cox]

Went back to just using BeamInterface

[steven-murray]

Looks correct to me!