test: migrate stats/base/dists/cosine/cdf to ULP-based assertions

[Planeshifter]

Resolves #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates stats/base/dists/cosine/cdf test files from the old computed EPS-based tolerance idiom (delta/tol with manual abs() comparisons) to ULP-based assertions using @stdlib/assert/is-almost-same-value.
• updates test/test.cdf.js, test/test.factory.js, and test/test.native.js. test/test.js was not touched, as it only contains basic export-shape assertions and does not use the tolerance idiom.
• the tightest ULP bound was determined agentically by running the full fixture set (positive_mean, negative_mean, large_variance) against the implementation and computing, for each fixture entry, the minimum ULP distance between the actual and expected values, then taking the maximum across all entries. The measured minimum is 1 ULP for all three fixture sets (and for both the main and factory code paths, which share the same underlying implementation). The test suite was run twice at this bound to confirm deterministic results.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352

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?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was written by Claude Code, running as an unattended scheduled task, following the conversion idiom established by prior merged PRs referencing #11352.

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@stdlib-js/reviewers

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Generated by Claude Code

[stdlib-bot]

Hello! 👋

We've noticed that you've been opening a number of PRs addressing good first issues. Thank you for your interest and enthusiasm!

Now that you've made a few contributions, we suggest no longer working on good first issues. Instead, we encourage you to prioritize cleaning up any PRs which have yet to be merged and then proceed to work on more involved tasks.

Not only does this ensure that other new contributors can work on things and get ramped up on all things stdlib, it also ensures that you can spend your time on more challenging problems. 🚀

For ideas for future PRs, feel free to search the codebase for TODOs and FIXMEs and be sure to check out other open issues on the issue tracker. Cheers!

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/cosine/cdf	$\\color{green}295/295$ $\\color{green}+100.00\\%$	$\\color{green}33/33$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}295/295$ $\\color{green}+100.00\\%$

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