feat: add math/base/special/gammaf

[nirmaljb]

---

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 status: passed
• task: lint_package_json status: passed
• task: lint_repl_help status: passed
• task: lint_javascript_src status: passed
• task: lint_javascript_cli status: na
• task: lint_javascript_examples status: passed
• task: lint_javascript_tests status: passed
• task: lint_javascript_benchmarks status: passed
• task: lint_python status: na
• task: lint_r status: passed
• task: lint_c_src status: passed
• task: lint_c_examples status: passed
• task: lint_c_benchmarks status: passed
• task: lint_c_tests_fixtures status: na
• task: lint_shell status: na
• task: lint_typescript_declarations status: passed
• task: lint_typescript_tests status: passed
• task: lint_license_headers status: passed ---

Progresses #649

Description

What is the purpose of this pull request?

This pull request:

• add Gammaf implementation (JavaScript + C)
• Test, Fixtures, Benchmark, Examples

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Add C implementations to base special math functions (tracking issue) #649

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.".

---

@stdlib-js/reviewers

[nirmaljb]

/stdlib update-copyright-years

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/gammaf	$\color{red}548/558$ $\color{green}+98.21%$	$\color{red}52/57$ $\color{green}+91.23%$	$\color{green}6/6$ $\color{green}+100.00%$	$\color{red}548/558$ $\color{green}+98.21%$

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

[nirmaljb]

Followed the cephes reference just like how it's followed in gamma. Where they have a fall-through, which cobbles the Stirling result.

The CI/CD marked it as an issue, so I had to comment it out. Anyways, Stirling result is a wasted compute.

[nirmaljb]

In the reference, the negative recurrence loop is commented out. All negative inputs are handled by the reflection formula.
So,
Only the positive-side test matters, just need to verify smallApprox is triggered when 0 < x < 1e-4 during the positive recurrence.

[nirmaljb]

The R fixture runner. R passes lint locally with a newer R version, but the CI runner has R 3.5.3, which is too old to install lintr (requires R ≥ 3.6). This appears to be an environment issue rather than a code issue; the same failure would occur for any package that includes an R file.

I also put it on zulip: #dev-questions > R lint CI failure — lintr not available for R 3.5.3

[nirmaljb]

using exp with float64tofloat32 wrapper on.
Until expf gets merged, this is the workaround.

[rautelaKamal]

Hey @nirmaljb! I noticed the CI check Lint Changed Files is failing. I checked out your branch locally and found a few strict JavaScript linting errors (ESLint) in lib/main.js. stdlib is very strict about spaces inside parentheses and around operators!

Here are the fixes needed in lib/main.js:

1. Line 104:

   // Change:
   if ( ( isIntegerf( x ) && x < 0 )|| isnanf( x ) || x === NINF ) {
   // To:
   if ( ( isIntegerf( x ) && x < 0 ) || isnanf( x ) || x === NINF ) {

2. Line 125:

   // Change:
   if ( (p&1) === 0 ) {
   // To:
   if ( ( p & 1 ) === 0 ) {

3. Line 150:

   // Change:
   z = stirlingApprox(x);
   // To:
   z = stirlingApprox( x );

4. Line 179:

   // Change:
   z = f32( ONE/z );
   // To:
   z = f32( ONE / z );

Also, in lib/polyval_p.js and lib/polyval_s.js, the expressions like (x * ( need spaces inside the parentheses: ( x * (.

Hope this helps you get those CI checks green so this awesome PR can get merged! 🚀

[Neerajpathak07]

A small advice here to prevent indentation errors in future would be to setup EditorConfig locally which adheres to the indentation rules stated in the already present .editorconfig file in stdlib.

[nirmaljb]

A small advice here to prevent indentation errors in future would be to setup EditorConfig locally which adheres to the indentation rules stated in the already present .editorconfig file in stdlib.

Actually, I believe I do have EditorConfig set up in my VS Code with the stdlib configuration.
I am not sure what could've gone wrong, but I will look into it.

But, anyways, thank you for the suggestion! @Neerajpathak07

[nirmaljb]

@rautelaKamal Thank you for your feedback! I will fix those inconsistencies.

[Neerajpathak07]

@nirmaljb just a quick heads-up the Lint error flagged here is for your fixtures/runner.py file. Would be better to take a look at that and compare it against a similar upstream implementation of math package which utilizes R to generate fixtures!!!