[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the test suites for stats/base/dists/frechet/skewness from relative tolerance testing to ULP difference testing, per [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352.
• replaces the delta/tol comparisons in test/test.js and test/test.native.js with t.strictEqual( isAlmostSameValue( y, expected[ i ], 244 ), true, 'returns expected value' );, adding the @stdlib/assert/is-almost-same-value require and dropping the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires. The existing expected[i] !== null guard (Julia emits null for parameter combinations having infinite skewness) is preserved.

ULP bound: 244 (both test/test.js and test/test.native.js), the measured minimum over the fixture set.

The bound was determined empirically rather than assumed: for every fixture, the minimum admissible bound was found by bisection over isAlmostSameValue, and the maximum over the full Julia fixture set (44 of 100 values are non-null and therefore compared) is exactly 244. The worst case is alpha = 4.750849820273925, s = 3.748713063341589 (y = 3.837909707867179 vs. expected 3.8379097078670705). Re-running the suite at 243 fails that single case, confirming 244 cannot be tightened further. The JS suite was then run twice at the final bound with identical results (59/59 passing), so the bound is not sensitive to run-to-run variation.

The previous relative tolerance was 140.0 * EPS, which is of comparable magnitude (140 * EPS corresponds to roughly 140–280 ULP depending on where a value falls within its binade), so this is not a loosening of the prior accuracy budget.

The native addon is not built in this environment, so test/test.native.js is skipped locally. To confirm that 244 is also correct for the C implementation, src/main.c was compiled directly against its transitive C dependency closure (math/base/special/gamma, math/base/special/pow, etc.) and evaluated over the same fixtures; its maximum ULP difference is likewise 244, attained on the same input. This matches the sibling conversions in this family (frechet/variance, frechet/kurtosis), which likewise use a single bound across both suites.

Only the two test files are modified; no implementation, fixture, or documentation changes are included.

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 authored by Claude Code running as an unattended scheduled task. It studied previously merged conversions under #11352 (including the frechet/variance and frechet/kurtosis siblings) to match the established idiom, applied the migration, measured the minimum ULP bound empirically against the fixtures (including a direct compilation of the C source to cover the skipped native suite), and verified that the tests pass and that the files lint cleanly.

---

@stdlib-js/reviewers

[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/frechet/skewness	$\\color{green}202/202$ $\\color{green}+100.00\\%$	$\\color{green}13/13$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}202/202$ $\\color{green}+100.00\\%$

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