docs: fix invalid NaN literal in C examples

[Planeshifter]

Description

What is the purpose of this pull request?

This pull request:

• fixes an invalid NaN literal in README C examples, propagating the correction from 1891207 ("docs: fix default value documentation").

Fixes an identical undefined-NaN usage in the C examples of dnanmidrange and dnanmeanwd READMEs, propagating the correction from dnanmin (commit 1891207). NaN is not a defined identifier in C without additional includes/macros; replaces both occurrences with 0.0/0.0, matching the pattern already used elsewhere in each README's full example and in sibling packages.

The PR originally also propagated the "natural logarithm" JSDoc qualifier from 6e22696 across 22 stats/base/dists log-PDF/CDF/PMF factories; per review, that change set was reverted on this branch (net diff no longer touches those files), as the qualifier insertion is to be reverted at its source instead.

Related Issues

Does this pull request have any related issues?

No.

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.

Validation: both sites were verified inside fenced C code blocks by two independent validation passes plus a style pass against sibling dnan* READMEs (dnanmin, dnanmeanpn, dnanmeanors, dnanmean), all of which use 0.0/0.0 in equivalent snippets. Note: open PR #10203 (C implementation for dnanmidrange) rewrites that README and may need a trivial rebase over the one-line fix.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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• Yes
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• Code generation (e.g., when writing an implementation or fixing a bug)
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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 as part of an automated fix-propagation routine: it identified generalizable fixes merged to develop in the last 24 hours, searched for sibling packages with the same defects, and applied the equivalent one-line fixes after multi-pass validation.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/ndarray/dnanmeanwd	$\\color{green}176/176$ $\\color{green}+0.00\\%$	$\\color{green}7/7$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}176/176$ $\\color{green}+0.00\\%$
stats/base/ndarray/dnanmidrange	$\\color{green}176/176$ $\\color{green}+0.00\\%$	$\\color{green}7/7$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}176/176$ $\\color{green}+0.00\\%$

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

[kgryte]

I think the insertion of "natural" was a mistake. Instead of updating the various descriptions in other stats packages, we should revert the change which inspired the changes in this PR.

[Planeshifter]

Reverted the natural qualifier changes on this branch and retitled the PR; the net diff is now only the two NaN → 0.0/0.0 C-example fixes in dnanmidrange and dnanmeanwd.

This PR does not revert 6e22696 itself — leaving that to a maintainer, since it also touched frechet package keywords. One data point for that revert: the affected packages' lib/main.js, lib/native.js, and inner factory docblocks currently read "natural logarithm" (as do 200+ other stats/base/dists files), so reverting only the outer factory line in frechet/logpdf re-introduces the intra-package inconsistency. If the intended direction is the shorter "logarithm of the ..." wording, that sweep would need to cover the wider set.

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Generated by Claude Code