feat: add JS implementation of `math/base/special/legendre-polynomial` by officiallyanee · Pull Request #10932 · stdlib-js/stdlib

officiallyanee · 2026-03-14T11:47:27Z

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: na
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: missing_dependencies
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: passed
task: lint_license_headers status: passed ---

Resolves #121 .

What is the purpose of this pull request?

This pull request:

adds the JS implementation of math/base/special/legendre-polynomial

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I could not understand initially why were tests were failing for non-integer value of n using lower tolerance so i did a ai code review and found a possible cause is hyp2f1

@stdlib-js/reviewers

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officiallyanee · 2026-03-14T11:49:01Z

/stdlib update-copyright-years

stdlib-bot · 2026-03-14T11:50:26Z

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/legendre-polynomial	$\color{green}212/212$ $\color{green}+0.00%$	$\color{green}24/24$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}212/212$ $\color{green}+0.00%$

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

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…a test --- 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: na - task: lint_package_json status: na - task: lint_repl_help status: na - task: lint_javascript_src status: passed - 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: missing_dependencies - 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 ---

Neerajpathak07

@officiallyanee Thanks for this!! A few comments:-
Why are we missing the repl.txt & LICENSE files?

Neerajpathak07 · 2026-04-10T11:54:14Z

lib/node_modules/@stdlib/math/base/special/legendre-polynomial/examples/index.js

+for ( i = 0; i < 100; i++ ) {
+	n = uniform( -50.0, 50.0 );
+	x = uniform( -1.0, 1.0 );
+	v = legendrepoly( n, x );
+	console.log( 'P_%d(%d) = %d', n, x, v );
+}


Apparently we have moved away from using a for to a recursive method using:-

var logEachMap = require( '@stdlib/console/log-each-map' );

Re:- https://github.com/stdlib-js/stdlib/blob/develop/lib/node_modules/%40stdlib/math/base/special/atan2d/examples/index.js

Ditto for makdown!!!

Neerajpathak07 · 2026-04-10T11:57:40Z

lib/node_modules/@stdlib/math/base/special/legendre-polynomial/test/test.js

+	expected = integerN.expected;
+
+	for ( i = 0; i < x.length; i++ ) {


Suggested change

expected = integerN.expected;

for ( i = 0; i < x.length; i++ ) {

expected = integerN.expected;

for ( i = 0; i < x.length; i++ ) {

applies here and below!!

Neerajpathak07 · 2026-04-10T12:00:27Z

lib/node_modules/@stdlib/math/base/special/legendre-polynomial/test/test.js

+			continue;
+		}
+		delta = abs( v - expected[ i ] );
+		tol = 1e13 * EPS * abs( expected[ i ] );


Increasing the tolerance by such huge value in-order to pass the test cases would not be viable. If the test cases are failing by large diffs then it might be better to take another closer look at the JS implementation and also see if your generated fixtures are well within the precision limit.

Oh yes, agreed! I looked into the problem with hyp2f1 and had a PR to improve it too: #11325 I will get back to this to see how much they improve meanwhile I will mark it draft for now

Neerajpathak07 · 2026-04-10T12:04:53Z

lib/node_modules/@stdlib/math/base/special/legendre-polynomial/test/test.js

+			continue;
+		}
+		delta = abs( v - expected[ i ] );
+		tol = 3700.0 * EPS * abs( expected[ i ] );


same comment here and below as well!!

officiallyanee · 2026-04-10T16:04:33Z

Thanks for all the suggestions @Neerajpathak07 . I will add the needful soon!

kgryte · 2026-04-10T20:05:47Z

Another comment: similar to sum-series, etc, I believe that this should be in math/base/tools, not math/base/special.

officiallyanee · 2026-04-10T21:45:22Z

@kgryte the #121 linked had this

Package: @stdlib/math/base/special/legendre-polynomial
Alias: base.legendrepoly

I will open a new PR or move it in this one, whichever would be better.

officiallyanee · 2026-04-10T22:55:11Z

/stdlib merge

…lynomial

kgryte · 2026-04-10T23:23:52Z

@officiallyanee You're right. Looking at SciPy, they also have evaluating a Legendre polynomial in their special namespace (ref: https://docs.scipy.org/doc/scipy/reference/generated/scipy.special.eval_legendre.html#scipy.special.eval_legendre).

It is fine to leave as is. Thanks for correcting.

stdlib-bot added Math Issue or pull request specific to math functionality. Needs Review A pull request which needs code review. labels Mar 14, 2026

stdlib-bot added the bot: In Progress Pull request is currently awaiting automation. label Mar 14, 2026

chore: update copyright years

3b5e828

stdlib-bot removed the bot: In Progress Pull request is currently awaiting automation. label Mar 14, 2026

officiallyanee marked this pull request as draft March 14, 2026 12:07

stdlib-bot removed the Needs Review A pull request which needs code review. label Mar 14, 2026

officiallyanee marked this pull request as ready for review March 14, 2026 18:29

stdlib-bot added the Needs Review A pull request which needs code review. label Mar 14, 2026

Neerajpathak07 requested changes Apr 10, 2026

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Neerajpathak07 added Needs Changes Pull request which needs changes before being merged. and removed Needs Review A pull request which needs code review. labels Apr 10, 2026

officiallyanee marked this pull request as draft April 10, 2026 16:06

stdlib-bot added the bot: In Progress Pull request is currently awaiting automation. label Apr 10, 2026

Merge remote-tracking branch 'upstream/develop' into feat/legendre-po…

ece1250

…lynomial

stdlib-bot removed the bot: In Progress Pull request is currently awaiting automation. label Apr 10, 2026

		expected = integerN.expected;

		for ( i = 0; i < x.length; i++ ) {

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