test: migrate stats/incr/pcorrmat to ULP-based assertions

[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/incr/pcorrmat from relative tolerance assertions to ULP-based assertions using @stdlib/assert/is-almost-same-value.
• replaces the if ( v === e ) { ... } else { delta/tol ... } branches in the four accumulator test cases with t.strictEqual( isAlmostSameValue( v, e, N ), true, 'returns expected value' );.
• removes the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires, along with the delta and tol declarations.

The previous assertions used a 3.0 * EPS * abs( e ) relative tolerance. The ULP bounds below are the minimum values which pass over the full set of fixture values:

Test case	ULP
incrementally computes a sample Pearson product-moment correlation matrix (order)	3
incrementally computes a sample Pearson product-moment correlation matrix (correlation matrix)	3
incrementally computes a sample Pearson product-moment correlation matrix (order, means)	1
incrementally computes a sample Pearson product-moment correlation matrix (correlation matrix, means)	1

Minimality was verified by lowering each bound by one ULP and confirming test failures (3 → 2 fails; 1 → 0 fails). The suite was run twice at the final bounds, with all 212 assertions passing in both runs (make test TESTS_FILTER=".*/stats/incr/pcorrmat/.*"). Only the test file is changed; the package has no test.native.js.

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, which performed the test migration and empirically determined the minimum ULP bounds.

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/pcorrmat	$\\color{green}545/545$ $\\color{green}+100.00\\%$	$\\color{green}47/47$ $\\color{green}+100.00\\%$	$\\color{green}6/6$ $\\color{green}+100.00\\%$	$\\color{green}545/545$ $\\color{green}+100.00\\%$

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