feat: add implementation of `stats/base/dists/wald/skewness` by bhargava-d16 · Pull Request #10206 · stdlib-js/stdlib

bhargava-d16 · 2026-02-10T20:32:34Z

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Progresses #209

Description

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This pull request:

adds an implementation of the skewness for the Wald (Inverse Gaussian) distribution.

Related Issues

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This pull request has the following related issues:

RFC: add the Wald distribution #209

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Read, understood, and followed the contributing guidelines.

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Signed-off-by: Bhargav Dabhade <bhargava2005dabhade@gmail.com> --- 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: na - task: lint_c_src status: missing_dependencies - task: lint_c_examples status: missing_dependencies - task: lint_c_benchmarks status: missing_dependencies - 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 ---

stdlib-bot · 2026-02-10T20:36:07Z

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/wald/skewness	$\color{green}185/185$ $\color{green}+0.00%$	$\color{green}10/10$ $\color{green}+0.00%$	$\color{green}2/2$ $\color{green}+0.00%$	$\color{green}185/185$ $\color{green}+0.00%$

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

Planeshifter

Thanks!

Planeshifter · 2026-02-12T05:59:04Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/README.md

+
+The [skewness][skewness] of a [Wald][wald-distribution] random variable with mean `μ` and shape parameter `λ > 0` is
+
+<!-- <equation class="equation" label="eq:rayleigh_skewness" align="center" raw="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" alt="Skewness for a Rayleigh distribution."> -->


Looks like there are a couple of copy-paste issues on this line - the equation label says rayleigh_skewness and the alt text says "Rayleigh distribution" instead of Wald.

Suggested change

Planeshifter · 2026-02-12T05:59:06Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/README.md

+\mathop{\mathrm{skew}}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}
+```
+
+<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" data-equation="eq:logistic_skewness">


Same kind of copy-paste issue here - the data-equation references the logistic distribution instead of Wald.

Suggested change

<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" data-equation="eq:logistic_skewness">

<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" data-equation="eq:wald_skewness">

Planeshifter · 2026-02-12T05:59:09Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/examples/c/example.c

+		mu = random_uniform( 0.1, 10.0 );
+		lambda = random_uniform( 0.1, 20.0 );
+		y = stdlib_base_dists_wald_skewness( mu, lambda );
+		printf( "µ: %.4f, λ: %.4f, Mean(X;µ,λ): %.4f\n", mu, lambda, y );


The printf label says "Mean" but this is computing skewness. The README's C example (line 215) has this correct already.

Suggested change

printf( "µ: %.4f, λ: %.4f, Mean(X;µ,λ): %.4f\n", mu, lambda, y );

printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );

--- 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: 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: na - 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: missing_dependencies - 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

Getting close, thanks! One more round of feedback.

Planeshifter · 2026-02-13T02:50:32Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/examples/c/example.c

+	double mu;
+	double lambda;


The variable declarations should be ordered by decreasing character length - lambda before mu. The README's C example (line 206) already has the correct order.

Suggested change

double mu;

double lambda;

double lambda;

double mu;

Planeshifter · 2026-02-13T02:50:34Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/lib/native.js

+// MAIN //
+
+/**
+* Returns the skewness of a Wald distribution with mean `mu` and shape parameter `lambda`.


Small consistency nit: main.js uses "Returns the skewness for a Wald distribution" but here it says "of a Wald distribution". The reference wald/mean package uses "for" consistently across both files. Let's match that here.

Suggested change

* Returns the skewness of a Wald distribution with mean `mu` and shape parameter `lambda`.

* Returns the skewness for a Wald distribution with mean `mu` and shape parameter `lambda`.

Planeshifter · 2026-02-13T04:50:35Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/README.md

+var mu = uniform( 10, EPS, 10.0, opts );
+var lambda = uniform( 10, EPS, 20.0, opts );
+
+logEachMap( 'µ: %0.4f, λ: %0.4f, Skewness(X;µ,λ): %0.4f', mu, lambda, skewness );


Suggested change

logEachMap( 'µ: %0.4f, λ: %0.4f, Skewness(X;µ,λ): %0.4f', mu, lambda, skewness );

logEachMap( 'µ: %0.4f, λ: %0.4f, skew(X;µ,λ): %0.4f', mu, lambda, skewness );

Planeshifter · 2026-02-13T04:50:46Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/README.md

+        mu = random_uniform( 0.1, 5.0 );
+        lambda = random_uniform( 0.1, 20.0 );
+        y = stdlib_base_dists_wald_skewness( mu, lambda );
+        printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );


Suggested change

printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );

printf( "µ: %.4f, λ: %.4f, skew(X;µ,λ): %.4f\n", mu, lambda, y );

Planeshifter · 2026-02-13T04:51:08Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/examples/c/example.c

+		mu = random_uniform( 0.1, 10.0 );
+		lambda = random_uniform( 0.1, 20.0 );
+		y = stdlib_base_dists_wald_skewness( mu, lambda );
+		printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );


Suggested change

printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );

printf( "µ: %.4f, λ: %.4f, skew(X;µ,λ): %.4f\n", mu, lambda, y );

Planeshifter · 2026-02-13T04:51:23Z

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/examples/index.js

+var mu = uniform( 10, EPS, 10.0, opts );
+var lambda = uniform( 10, EPS, 20.0, opts );
+
+logEachMap( 'µ: %0.4f, λ: %0.4f, skewness(X;µ,λ): %0.4f', mu, lambda, skewness );


Suggested change

logEachMap( 'µ: %0.4f, λ: %0.4f, skewness(X;µ,λ): %0.4f', mu, lambda, skewness );

logEachMap( 'µ: %0.4f, λ: %0.4f, skew(X;µ,λ): %0.4f', mu, lambda, skewness );

--- 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: na - 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: na - 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: missing_dependencies - 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 ---

bhargava-d16 · 2026-02-14T04:37:52Z

@Planeshifter I have made the requested changes. Please let me know if there are any further changes to be made

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/benchmark/c/benchmark.c

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/README.md

lib/node_modules/@stdlib/stats/base/dists/wald/skewness/benchmark/c/benchmark.c

Signed-off-by: Philipp Burckhardt <pburckhardt@outlook.com>

Planeshifter

Let's get this one in... Thanks!

stdlib-bot · 2026-02-14T05:20:08Z

PR Commit Message

feat: add implementation of `stats/base/dists/wald/skewness`

PR-URL: https://github.com/stdlib-js/stdlib/pull/10206
Ref: https://github.com/stdlib-js/stdlib/issues/209

Co-authored-by: Philipp Burckhardt <pburckhardt@outlook.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>
Signed-off-by: Bhargav Dabhade <bhargava2005dabhade@gmail.com>
Signed-off-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 Feb 10, 2026

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chore: minor changes for consistency

75f873d

Signed-off-by: Philipp Burckhardt <pburckhardt@outlook.com>

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		The [skewness][skewness] of a [Wald][wald-distribution] random variable with mean `μ` and shape parameter `λ > 0` is

		<!-- <equation class="equation" label="eq:rayleigh_skewness" align="center" raw="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" alt="Skewness for a Rayleigh distribution."> -->

	<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" data-equation="eq:logistic_skewness">
	<!-- <div class="equation" align="center" data-raw-text="\operatorname{skew}\left( X \right) = 3 \sqrt{\frac{\mu}{\lambda}}" data-equation="eq:wald_skewness">

	printf( "µ: %.4f, λ: %.4f, Mean(X;µ,λ): %.4f\n", mu, lambda, y );
	printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );

	* Returns the skewness of a Wald distribution with mean `mu` and shape parameter `lambda`.
	* Returns the skewness for a Wald distribution with mean `mu` and shape parameter `lambda`.

	logEachMap( 'µ: %0.4f, λ: %0.4f, Skewness(X;µ,λ): %0.4f', mu, lambda, skewness );
	logEachMap( 'µ: %0.4f, λ: %0.4f, skew(X;µ,λ): %0.4f', mu, lambda, skewness );

	printf( "µ: %.4f, λ: %.4f, Skewness(X;µ,λ): %.4f\n", mu, lambda, y );
	printf( "µ: %.4f, λ: %.4f, skew(X;µ,λ): %.4f\n", mu, lambda, y );

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