NEW: Implement multislice propagation operator with correct adjoint

[carterbox]

Purpose

Implement a correct adjoint operation for multi-slice propagation.

Approach

• Replace placeholder class with correctly implemented MultiSlice operator
  • Adjoint function is double adjoint instead of separate for probe and object
• Remove unused specialized adjoint methods from the Ptycho operator because these methods would require reimplementation to work with the new MultiSlice operator
• Implement new operator tests for the new MultiSlice and Ptycho Operator APIs; these tests prove that the adjoint operations are correct

Pre-Merge Checklists

Submitter

• Write a helpfully descriptive pull request title.
• Organize changes into logically grouped commits with descriptive commit messages.
• Document all new functions.
• Click 'details' on the readthedocs check to view the updated docs.
• Write tests for new functions or explain why they are not needed.
• Address any complaints from pep8speaks.

Reviewer

• Actually read all of the code.
• Run the new code yourself; the included tests should make this easy.
• Write a summary of the changes as you understand them.
• Thank the submitter.

[pep8speaks]

Hello @carterbox! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file src/tike/operators/cupy/convolution.py:

Line 107:81: E501 line too long (85 > 80 characters)

• In the file tests/operators/test_multislice.py:

Line 32:81: E501 line too long (83 > 80 characters)
Line 70:81: E501 line too long (81 > 80 characters)
Line 71:81: E501 line too long (81 > 80 characters)
Line 72:81: E501 line too long (81 > 80 characters)
Line 97:81: E501 line too long (83 > 80 characters)

• In the file tests/operators/test_ptycho.py:

Line 32:81: E501 line too long (83 > 80 characters)
Line 69:81: E501 line too long (81 > 80 characters)
Line 70:81: E501 line too long (81 > 80 characters)
Line 71:81: E501 line too long (81 > 80 characters)

Comment last updated at 2024-06-05 19:32:16 UTC

[a4894z]

I was trying to actually run these changes on some benchmarking data, but it was ending up looking like the multislice_fwd_infrastructure branch which kinda was defeating the point of splitting the PR up like this.

By eye, it looks OK but I haven't tested it in ePIE yet.

[carterbox]

Thanks, @a4894z. I think the way to test this PR was to just run the included adjoint tests. Reading through the changes to check for understandable documentation and typos and copypasta are also helpful.