test: migrate constants/float32/ln-half to ULP-based assertions

[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the test suite for constants/float32/ln-half from a relative tolerance assertion to a ULP difference assertion.

The export equals lnf(0.5) test previously computed delta = absf( v - FLOAT32_LN_HALF ) and tol = EPS and asserted with t.ok( delta <= tol, ... ). It now delegates to @stdlib/number/float32/base/assert/is-almost-same-value:

tape( 'export equals `lnf(0.5)`', function test( t ) {
	var v = lnf( 0.5 );
	t.strictEqual( isAlmostSameValue( v, FLOAT32_LN_HALF, 0 ), true, 'returns expected value' );
	t.end();
});

Final ULP constant: 0.

File	Call sites	ULP bound
test/test.js	1	0

Notes on how the bound was measured:

• The bound was tightened empirically, starting from n = 64 and stepping down (64, 32, 16, 8, 4, 2, 1, 0). Every probe passes, so 0 is the measured minimum and no smaller non-negative bound exists.
• lnf( 0.5 ) returns -0.6931471824645996, which is bit-identical to the exported constant -0.6931471824645996; @stdlib/number/float32/base/ulp-difference reports a difference of exactly 0 ULP. The single-precision variant of the assertion is used here (matching the already-converted constants/float32/ln-two, constants/float32/pi-squared, and constants/float32/half-ln-two) so that the gap is measured in single-precision units.
• The suite was run twice at the final bound to confirm determinism; all 4 assertions pass both times.
• This package has no test.native.js, so there is no JS/C divergence to account for.
• The two pre-existing exact assertions (typeof and the exact value check) are intentionally left unchanged, as exact comparisons remain correct there.
• Only the one test file is modified; no source, documentation, or fixture 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 bound is reproducible across architectures: the comparison is between two compile-time-fixed single-precision values and is not subject to FMA-contraction differences.

make eslint-tests TESTS_FILTER=".*/constants/float32/ln-half/.*" and make test TESTS_FILTER=".*/constants/float32/ln-half/.*" both pass. The changed file was additionally verified for tabs-only indentation, no new trailing whitespace, LF endings, and a final newline.

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. It studied the already-converted packages in the same family (notably constants/float32/ln-two and constants/float16/ln-half) to match the established idiom, then measured the minimum ULP bound empirically and verified determinism as described above.

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@stdlib-js/reviewers

🤖 Generated with Claude Code

https://claude.ai/code/session_0145oPrciok5CLgLVy5bna7i

---

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.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
constants/float32/ln-half	$\\color{green}55/55$ $\\color{green}+100.00\\%$	$\\color{green}1/1$ $\\color{green}+100.00\\%$	$\\color{green}0/0$ $\\color{green}+100.00\\%$	$\\color{green}55/55$ $\\color{green}+100.00\\%$

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