feat: add C implementation for `stats/base/dists/f/pdf` by rautelaKamal · Pull Request #11201 · stdlib-js/stdlib

rautelaKamal · 2026-03-29T14:04:24Z

Description

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This pull request:

Implements a native C-port for the F Distribution Probability Density Function (@stdlib/stats/base/dists/f/pdf).
Configures include.gypi, binding.gyp, and manifest.json dependencies via internal N-API mechanisms (STDLIB_MATH_BASE_NAPI_MODULE_DDD_D).
Validates identical sub-epsilon behavior to pure JS implementation across boundaries, limits, and NaN.
Introduces robust Boost and Julia test.native.js fixtures to validate the C-port accuracy and benchmarks it.

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Other

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This is a Proof of Concept submission towards my GSoC 2026 application regarding porting distributions and specific math functions to high-performance C native addons.

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Read, understood, and followed the contributing guidelines.

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stdlib-bot · 2026-03-29T14:08:09Z

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/f/pdf	$\\color{red}599/647$ $\\color{green}+0.00\\%$	$\\color{red}62/66$ $\\color{green}+0.00\\%$	$\\color{green}6/6$ $\\color{green}+0.00\\%$	$\\color{red}599/647$ $\\color{green}+0.00\\%$

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

rautelaKamal · 2026-03-29T14:25:43Z

Just a quick heads up regarding the minor coverage drop flagged by Codecov:

The native.js file is showing 0% function coverage because the addon.node binary correctly skips compilation during the CI coverage step, which triggers the expected opts.skip = true fallback inside test.native.js. The math logic is fully tested and verified when the native addon actually builds!

Also, the drop in ibeta_power_terms.js relates to the original pure JavaScript implementations and was untouched in this PR. @Planeshifter

Neerajpathak07 · 2026-03-31T06:12:50Z

@rautelaKamal FYI: I think you have misunderstood what we do for adding native implementation. Here we expect to add the corresponding C files for benchmark, examples and the main implementation alongside the relevant dependencies and documentations.
Take a look at a few of the merged PR's on how this is done.
For eg:- refer to https://github.com/stdlib-js/stdlib/pull/10839/changes

rautelaKamal · 2026-03-31T06:38:17Z

@Neerajpathak07 Thank you for catching this and pointing me to the reference PR! I totally misunderstood the scope, I was focused solely on evaluating the N-API/Node.js boundary and completely neglected the standalone C ecosystem deliverables.

I have just pushed an update that adds the benchmark/c/ and examples/c/ directories, the src/Makefile for cleanup, and the full C APIs documentation section in the README.md.

Really appreciate you taking the time to explain the standard.Please let me know if there's anything else I missed!

Lokeshranjan8 · 2026-03-31T17:24:30Z

@rautelaKamal Update your commit message

feat(stats/base/dists/f/pdf): add native C addon for evaluating the PDF

to the following

feat: add C implementation for stats/base/dists/f/pdf

The C usage example in both the README and the `src/main.c` `@example` annotated `stdlib_base_dists_f_pdf( 2.0, 1.0, 1.0 )` as returning `~0.127`, but the correct value is `~0.075`. Since CI does not execute C example comments, the error would otherwise ship. A baseline assertion mirroring the corrected value is added to the native test to guard against regressions. --- type: pre_commit_static_analysis_report description: Results of running static analysis checks when committing changes. report: - task: lint_filenames status: passed - task: lint_editorconfig status: passed - task: lint_markdown_pkg_readmes status: passed - task: lint_markdown_docs status: na - task: lint_markdown status: na - task: lint_package_json status: na - task: lint_repl_help status: na - task: lint_javascript_src status: na - task: lint_javascript_cli status: na - task: lint_javascript_examples status: na - task: lint_javascript_tests status: passed - task: lint_javascript_benchmarks status: na - task: lint_python status: na - task: lint_r status: na - task: lint_c_src status: passed - task: lint_c_examples status: na - task: lint_c_benchmarks status: na - task: lint_c_tests_fixtures status: na - task: lint_shell status: na - task: lint_typescript_declarations status: passed - task: lint_typescript_tests status: na - task: lint_license_headers status: passed ---

The native C implementation computes the log-PDF via betaln+exp, which differs from the JS reference value by 2 ULP for pdf(2,1,1). The baseline assertion used a 1-ULP tolerance, causing the native test to fail in CI. --- type: pre_commit_static_analysis_report description: Results of running static analysis checks when committing changes. report: - task: lint_filenames status: passed - task: lint_editorconfig status: passed - task: lint_markdown_pkg_readmes status: na - task: lint_markdown_docs status: na - task: lint_markdown status: na - task: lint_package_json status: na - task: lint_repl_help status: na - task: lint_javascript_src status: na - task: lint_javascript_cli status: na - task: lint_javascript_examples status: na - task: lint_javascript_tests status: passed - task: lint_javascript_benchmarks status: na - task: lint_python status: na - task: lint_r status: na - task: lint_c_src status: na - task: lint_c_examples status: na - task: lint_c_benchmarks status: na - task: lint_c_tests_fixtures status: na - task: lint_shell status: na - task: lint_typescript_declarations status: passed - task: lint_typescript_tests status: na - task: lint_license_headers status: passed ---

Planeshifter

Last but not least, let's land this PR of yours, @rautelaKamal!

stdlib-bot · 2026-07-05T06:21:55Z

PR Commit Message

feat: add C implementation for `stats/base/dists/f/pdf`

PR-URL: https://github.com/stdlib-js/stdlib/pull/11201

Co-authored-by: Philipp Burckhardt <pburckhardt@outlook.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Please review the above commit message and make any necessary adjustments.

stdlib-bot added Statistics Issue or pull request related to statistical functionality. Needs Review A pull request which needs code review. labels Mar 29, 2026

github-actions Bot mentioned this pull request Mar 29, 2026

[aw] No-Op Runs #11033

Closed

This was referenced Mar 30, 2026

[RFC]: Develop native C implementations for probability distribution functions stdlib-js/google-summer-of-code#222

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[RFC]: Develop native C implementations for probability distribution functions stdlib-js/google-summer-of-code#223

Closed

rautelaKamal force-pushed the feat/stats-base-dists-f-pdf-c-port branch from 9744905 to 197e55f Compare March 31, 2026 18:19

rautelaKamal changed the title ~~feat(stats/base/dists/f/pdf): add native C addon for evaluating the PDF~~ feat: add C implementation for stats/base/dists/f/pdf Apr 4, 2026

rautelaKamal force-pushed the feat/stats-base-dists-f-pdf-c-port branch from 8be84d0 to 4bf98b2 Compare April 5, 2026 18:44

stdlib-bot added the Merge Conflicts Pull request which has merge conflicts. label Apr 7, 2026

rautelaKamal closed this Apr 7, 2026

rautelaKamal force-pushed the feat/stats-base-dists-f-pdf-c-port branch from 4bf98b2 to 68e429f Compare April 7, 2026 11:49

stdlib-bot removed the Needs Review A pull request which needs code review. label Apr 7, 2026

rautelaKamal reopened this Apr 12, 2026

stdlib-bot removed the Merge Conflicts Pull request which has merge conflicts. label Apr 14, 2026

rautelaKamal force-pushed the feat/stats-base-dists-f-pdf-c-port branch from e73fb48 to 0f35a65 Compare April 14, 2026 18:28

rautelaKamal requested a review from a team April 20, 2026 13:13

stdlib-bot added the Needs Review A pull request which needs code review. label Apr 20, 2026

Planeshifter mentioned this pull request Jul 5, 2026

Clean-up and land statistical distribution PRs stdlib-js/metr-issue-tracker#966

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Planeshifter force-pushed the feat/stats-base-dists-f-pdf-c-port branch from b97480f to 647e413 Compare July 5, 2026 05:35

rautelaKamal and others added 3 commits July 5, 2026 01:16

feat: add C implementation for stats/base/dists/f/pdf

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Planeshifter force-pushed the feat/stats-base-dists-f-pdf-c-port branch from 647e413 to 2ff7ac9 Compare July 5, 2026 06:16

Planeshifter changed the title ~~feat: add C implementation for stats/base/dists/f/pdf~~ feat: add C implementation for stats/base/dists/f/pdf Jul 5, 2026

Planeshifter approved these changes Jul 5, 2026

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Planeshifter added the Ready To Merge A pull request which is ready to be merged. label Jul 5, 2026

stdlib-bot removed the Needs Review A pull request which needs code review. label Jul 5, 2026

Planeshifter merged commit 82d0e4a into stdlib-js:develop Jul 5, 2026
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stdlib-bot removed the Ready To Merge A pull request which is ready to be merged. label Jul 5, 2026

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feat: add C implementation for `stats/base/dists/f/pdf`#11201

feat: add C implementation for `stats/base/dists/f/pdf`#11201
Planeshifter merged 3 commits into
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