https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor
Kumaraswamy's double bounded distribution constructor.
https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor
cdf class constructor ctor dist distribution javascript kumaraswamy node node-js nodejs object pdf prob probability properties quantile statistics stats stdlib
Last synced: 30 days ago
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Kumaraswamy's double bounded distribution constructor.
- Host: GitHub
- URL: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-15T17:40:57.000Z (about 5 years ago)
- Default Branch: main
- Last Pushed: 2026-06-10T04:19:04.000Z (2 months ago)
- Last Synced: 2026-06-10T05:16:07.771Z (2 months ago)
- Topics: cdf, class, constructor, ctor, dist, distribution, javascript, kumaraswamy, node, node-js, nodejs, object, pdf, prob, probability, properties, quantile, statistics, stats, stdlib
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 2.29 MB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
- Notice: NOTICE
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README
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# Kumaraswamy
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Kumaraswamy's double bounded distribution constructor.
## Installation
```bash
npm install @stdlib/stats-base-dists-kumaraswamy-ctor
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
## Usage
```javascript
var Kumaraswamy = require( '@stdlib/stats-base-dists-kumaraswamy-ctor' );
```
#### Kumaraswamy( \[a, b] )
Returns a [Kumaraswamy's double bounded][kumaraswamy-distribution] distribution object.
```javascript
var kumaraswamy = new Kumaraswamy();
var mu = kumaraswamy.mean;
// returns 0.5
```
By default, `a = 1.0` and `b = 1.0`. To create a distribution having a different `a` (first shape parameter) and `b` (second shape parameter), provide the corresponding arguments.
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var mu = kumaraswamy.mean;
// returns ~0.406
```
* * *
## kumaraswamy
A [Kumaraswamy's double bounded][kumaraswamy-distribution] distribution object has the following properties and methods...
### Writable Properties
#### kumaraswamy.a
First shape parameter of the distribution. `a` **must** be a positive number.
```javascript
var kumaraswamy = new Kumaraswamy();
var a = kumaraswamy.a;
// returns 1.0
kumaraswamy.a = 3.0;
a = kumaraswamy.a;
// returns 3.0
```
#### kumaraswamy.b
Second shape parameter of the distribution. `b` **must** be a positive number.
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var b = kumaraswamy.b;
// returns 4.0
kumaraswamy.b = 3.0;
b = kumaraswamy.b;
// returns 3.0
```
* * *
### Computed Properties
#### Kumaraswamy.prototype.kurtosis
Returns the [excess kurtosis][kurtosis].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var kurtosis = kumaraswamy.kurtosis;
// returns ~2.704
```
#### Kumaraswamy.prototype.mean
Returns the [expected value][expected-value].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var mu = kumaraswamy.mean;
// returns ~0.481
```
#### Kumaraswamy.prototype.mode
Returns the [mode][mode].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var mode = kumaraswamy.mode;
// returns ~0.503
```
#### Kumaraswamy.prototype.skewness
Returns the [skewness][skewness].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var skewness = kumaraswamy.skewness;
// returns ~-0.201
```
#### Kumaraswamy.prototype.stdev
Returns the [standard deviation][standard-deviation].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var s = kumaraswamy.stdev;
// returns ~0.13
```
#### Kumaraswamy.prototype.variance
Returns the [variance][variance].
```javascript
var kumaraswamy = new Kumaraswamy( 4.0, 12.0 );
var s2 = kumaraswamy.variance;
// returns ~0.017
```
* * *
### Methods
#### Kumaraswamy.prototype.cdf( x )
Evaluates the [cumulative distribution function][cdf] (CDF).
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var y = kumaraswamy.cdf( 0.5 );
// returns ~0.684
```
#### Kumaraswamy.prototype.logcdf( x )
Evaluates the natural logarithm of the [cumulative distribution function][cdf] (CDF).
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var y = kumaraswamy.logcdf( 0.5 );
// returns ~-0.38
```
#### Kumaraswamy.prototype.logpdf( x )
Evaluates the natural logarithm of the [probability density function][pdf] (PDF).
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var y = kumaraswamy.logpdf( 0.8 );
// returns ~-1.209
```
#### Kumaraswamy.prototype.pdf( x )
Evaluates the [probability density function][pdf] (PDF).
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var y = kumaraswamy.pdf( 0.8 );
// returns ~0.299
```
#### Kumaraswamy.prototype.quantile( p )
Evaluates the [quantile function][quantile-function] at probability `p`.
```javascript
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var y = kumaraswamy.quantile( 0.5 );
// returns ~0.399
y = kumaraswamy.quantile( 1.9 );
// returns NaN
```
* * *
## Examples
```javascript
var Kumaraswamy = require( '@stdlib/stats-base-dists-kumaraswamy-ctor' );
var kumaraswamy = new Kumaraswamy( 2.0, 4.0 );
var mu = kumaraswamy.mean;
// returns ~0.406
var mode = kumaraswamy.mode;
// returns ~0.378
var s2 = kumaraswamy.variance;
// returns ~0.035
var y = kumaraswamy.cdf( 0.8 );
// returns ~0.983
```
* * *
## Notice
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
## License
See [LICENSE][stdlib-license].
## Copyright
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/stats-base-dists-kumaraswamy-ctor.svg
[npm-url]: https://npmjs.org/package/@stdlib/stats-base-dists-kumaraswamy-ctor
[test-image]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-base-dists-kumaraswamy-ctor/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/stats-base-dists-kumaraswamy-ctor?branch=main
[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-dists-kumaraswamy-ctor/main/LICENSE
[kumaraswamy-distribution]: https://en.wikipedia.org/wiki/Kumaraswamy_distribution
[cdf]: https://en.wikipedia.org/wiki/Cumulative_distribution_function
[pdf]: https://en.wikipedia.org/wiki/Probability_density_function
[quantile-function]: https://en.wikipedia.org/wiki/Quantile_function
[expected-value]: https://en.wikipedia.org/wiki/Expected_value
[kurtosis]: https://en.wikipedia.org/wiki/Kurtosis
[mode]: https://en.wikipedia.org/wiki/Mode_%28statistics%29
[skewness]: https://en.wikipedia.org/wiki/Skewness
[standard-deviation]: https://en.wikipedia.org/wiki/Standard_deviation
[variance]: https://en.wikipedia.org/wiki/Variance