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

[kgryte]

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/base/dists/cosine/stdev from relative tolerance (EPS-based) comparisons to ULP-based assertions, per [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352.

Specifically, in both test/test.js and test/test.native.js, the fixture loop's delta/tol computation is replaced with

t.strictEqual( isAlmostSameValue( y, expected[ i ], 1 ), true, 'returns expected value' );

adding a @stdlib/assert/is-almost-same-value require and dropping the now-unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires.

Final ULP constant: 1 (both test.js and test.native.js).

The bound was tightened empirically rather than assumed. Starting from 64, the minimum passing integer over the full fixture set (100 non-null cases) is 1:

• at N = 0: 36 of 110 assertions fail;
• at N = 1: 110/110 pass.

The maximum observed ULP difference across the fixtures is exactly 1 ULP.

test.js was run twice at the final N with identical results. The native test is skipped locally (the addon is not built in this environment), but the same bound is safe by construction: src/main.c and lib/main.js both compute s * 0.36151205519132795 using the identical constant. A single IEEE-754 double multiplication is correctly rounded and admits no FMA contraction, so the native result is bit-identical to the JavaScript result and the measured 1 ULP bound carries over.

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

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.

The full project toolchain could not be installed in the authoring environment: make install-node-modules fails with ETARGET: No matching version found for es-object-atoms@^1.1.2 (the registry reachable from that environment publishes only up to 1.1.1), so make init and the project eslint configuration could not be run. As a workaround, tape was installed in an isolated scratch directory to execute the package's test suite, and the changed files were linted against core rules (no-unused-vars, no-undef, no-trailing-spaces, no-mixed-spaces-and-tabs, one-var, vars-on-top, semi, eqeqeq, no-irregular-whitespace), which report clean. The diff otherwise mirrors the idiom of previously merged conversions (e.g. #14163, #14155) verbatim. Leaving this as a draft so CI can confirm the full lint and native builds.

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. It surveyed prior merged conversions to match the established idiom, applied the test changes, and determined the minimum ULP bound empirically by bisecting the constant against the full fixture set.

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@stdlib-js/reviewers

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Generated by Claude Code

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/cosine/stdev	$\\color{green}180/180$ $\\color{green}+100.00\\%$	$\\color{green}9/9$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}180/180$ $\\color{green}+100.00\\%$

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