replace fwd_scale with norm kwarg in mkl_fft

[vtavana]

Both NumPy and SciPy use norm parameter which is the normalization mode that is used scaling the FFT results. mkl_fft has the scaling parameter fwd_scale directly. In this PR, fwd_scale is replaced with norm to be aligned with NumPy and SciPy.

[antonwolfy]

LGTM! Thank you @vtavana

[ndgrigorian]

LGTM

[Copilot]

Pull Request Overview

This PR replaces the fwd_scale parameter with norm parameter in mkl_fft functions to align with NumPy and SciPy FFT interfaces. The change makes the API more consistent with standard FFT libraries.

• Replaced fwd_scale parameter with norm parameter across all FFT functions
• Updated function signatures in both interface modules and core implementation
• Modified tests to use norm parameter instead of fwd_scale

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
mkl_fft/_mkl_fft.py	Updated core FFT function signatures to use norm parameter and added internal computation of forward scale factor
mkl_fft/interfaces/_scipy_fft.py	Removed _compute_fwd_scale usage and passed norm directly to underlying FFT functions
mkl_fft/interfaces/_numpy_fft.py	Removed _compute_fwd_scale usage and passed norm directly to underlying FFT functions
mkl_fft/tests/test_fftnd.py	Updated test cases to use norm parameter, removed scaling-specific test class, added None value test
mkl_fft/_fft_utils.py	Minor string formatting improvements unrelated to main change
README.md	Updated function signatures in documentation to reflect norm parameter
CHANGELOG.md	Added entry documenting the parameter replacement

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