feat: add fft/base/fftpack/ndarray/float64/cosqi

[gunjjoshi]

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Resolves stdlib-js/metr-issue-tracker#1130.

Description

What is the purpose of this pull request?

This pull request:

• adds fft/base/fftpack/ndarray/float64/cosqi, which will be the one-dimensional double-precision floating-point ndarray wrapper for fft/base/fftpack/generic/cosqi.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: add fft/base/fftpack/ndarray/dcosqi metr-issue-tracker#1130.

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

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• Test/benchmark generation
• Documentation (including examples)
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Used Claude Code to review the implementation.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
fft/base/fftpack/ndarray/float64/cosqi	$\\color{green}149/149$ $\\color{green}+0.00\\%$	$\\color{green}3/3$ $\\color{green}+0.00\\%$	$\\color{green}1/1$ $\\color{green}+0.00\\%$	$\\color{green}149/149$ $\\color{green}+0.00\\%$

The above coverage report was generated for the changes in this PR.

[gunjjoshi]

I have updated this PR now. The latest commit 5f9ea6c now contains similar changes as done in the commit 3a9ce20 of #14085.

This is now ready for review.

[kgryte]

Left initial comments.

[gunjjoshi]

I noticed this now. We describe N as the number of elements in the input ndarray, which is wrong. N is the length of the sequence that would be transformed, and not the number of eleemnts in the input ndarray (which is, 3*N + 34). I will update this here and will fix it for other packages in follow-up PRs.

[gunjjoshi]

Done in e2006d4.

[gunjjoshi]

If the updated line here seems fine, I'll go ahead and update the notes sections of existing packages too.

[kgryte]

Yes, this seems fine.

[kgryte]

...and updating the existing applicable packages would be appreciated! Cheers!

[kgryte]

LGTM