Replace tranposes with .mT

[jank324]

Description

Sub- / replacement PR for #538.

We've seen that the fastest transpose operation in PyTorch seems to be x.mT.

Motivation and Context

• I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

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• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.
• I have reformatted the code and checked that formatting passes (required).
• I have have fixed all issues found by flake8 (required).
• I have ensured that all pytest tests pass (required).
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[jank324]

[jank324]

[jank324]

I think in this case the code readability is even slightly improved. Considering the speed up is only 200 ns per call, and the number of calls not that large, the lack of a visible overall speedup is not surprising. Despite this, I think we can and should merge this.

[Copilot]

Pull Request Overview

This PR improves performance by replacing various PyTorch transpose operations with the faster .mT property. Based on benchmarking, .mT is the fastest transpose operation in PyTorch for matrix transposition.

• Replace torch.transpose() and .transpose() calls with .mT across multiple files
• Update code formatting to use single-line expressions where applicable
• Add performance documentation to contribution guidelines

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/test_statistics.py	Replace .T with .mT in test covariance calculation
cheetah/utils/statistics.py	Use .mT for transpose in weighted covariance matrix computation
cheetah/utils/kde.py	Replace .transpose() with .mT in kernel density estimation
cheetah/track_methods.py	Update transpose operations in transfer matrix calculations
cheetah/particles/particle_beam.py	Replace transpose operations in particle transformation
cheetah/accelerator/screen.py	Update transpose usage in beam reading methods
cheetah/accelerator/element.py	Use .mT in first-order transfer map tracking
cheetah/accelerator/dipole.py	Replace transpose in dipole transfer map calculations
cheetah/accelerator/cavity.py	Update transpose operations in cavity tracking
CONTRIBUTING.md	Add performance guidance for transpose operations
CHANGELOG.md	Document performance improvements

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[jank324]

[jank324]

These results are really weird ... especially because the drift-kick-drift code wasn't touched. In theory this must therefore be noise. 🤔

[Copilot]

Pull Request Overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

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