https://github.com/stdlib-js/stats-base-dists-chisquare-ctor
Chi-squared distribution constructor.
https://github.com/stdlib-js/stats-base-dists-chisquare-ctor
chi chi-squared chisquare chisquared class constructor ctor dist distribution javascript node node-js nodejs object prob probability squared statistics stats stdlib
Last synced: 8 months ago
JSON representation
Chi-squared distribution constructor.
- Host: GitHub
- URL: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-15T17:39:08.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2024-12-30T02:57:13.000Z (9 months ago)
- Last Synced: 2024-12-30T03:27:13.787Z (9 months ago)
- Topics: chi, chi-squared, chisquare, chisquared, class, constructor, ctor, dist, distribution, javascript, node, node-js, nodejs, object, prob, probability, squared, statistics, stats, stdlib
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 4.15 MB
- Stars: 1
- Watchers: 3
- 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
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README
About stdlib...
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# ChiSquare
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Chi-squared distribution constructor.
## Installation
```bash
npm install @stdlib/stats-base-dists-chisquare-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 ChiSquare = require( '@stdlib/stats-base-dists-chisquare-ctor' );
```
#### ChiSquare( \[k] )
Returns an [chi-squared][chisquare-distribution] distribution object.
```javascript
var chisquare = new ChiSquare();
var mu = chisquare.mean;
// returns 1.0
```
By default, `k = 1.0`. To create a distribution having a different degrees of freedom `k`, provide a parameter value.
```javascript
var chisquare = new ChiSquare( 4.0 );
var mu = chisquare.mean;
// returns 4.0
```
* * *
## chisquare
A [chi-squared][chisquare-distribution] distribution object has the following properties and methods...
### Writable Properties
#### chisquare.k
Rate parameter of the distribution. `k` **must** be a positive number.
```javascript
var chisquare = new ChiSquare( 2.0 );
var k = chisquare.k;
// returns 2.0
chisquare.k = 3.0;
k = chisquare.k;
// returns 3.0
```
* * *
### Computed Properties
#### ChiSquare.prototype.entropy
Returns the [differential entropy][entropy].
```javascript
var chisquare = new ChiSquare( 4.0 );
var entropy = chisquare.entropy;
// returns ~2.27
```
#### ChiSquare.prototype.kurtosis
Returns the [excess kurtosis][kurtosis].
```javascript
var chisquare = new ChiSquare( 4.0 );
var kurtosis = chisquare.kurtosis;
// returns 3.0
```
#### ChiSquare.prototype.mean
Returns the [expected value][expected-value].
```javascript
var chisquare = new ChiSquare( 4.0 );
var mu = chisquare.mean;
// returns 4.0
```
#### ChiSquare.prototype.median
Returns the [median][median].
```javascript
var chisquare = new ChiSquare( 4.0 );
var median = chisquare.median;
// returns ~3.357
```
#### ChiSquare.prototype.mode
Returns the [mode][mode].
```javascript
var chisquare = new ChiSquare( 4.0 );
var mode = chisquare.mode;
// returns 2.0
```
#### ChiSquare.prototype.skewness
Returns the [skewness][skewness].
```javascript
var chisquare = new ChiSquare( 4.0 );
var skewness = chisquare.skewness;
// returns ~1.414
```
#### ChiSquare.prototype.stdev
Returns the [standard deviation][standard-deviation].
```javascript
var chisquare = new ChiSquare( 4.0 );
var s = chisquare.stdev;
// returns ~2.828
```
#### ChiSquare.prototype.variance
Returns the [variance][variance].
```javascript
var chisquare = new ChiSquare( 4.0 );
var s2 = chisquare.variance;
// returns 8.0
```
* * *
### Methods
#### ChiSquare.prototype.cdf( x )
Evaluates the [cumulative distribution function][cdf] (CDF).
```javascript
var chisquare = new ChiSquare( 2.0 );
var y = chisquare.cdf( 0.5 );
// returns ~0.221
```
#### ChiSquare.prototype.mgf( t )
Evaluates the [moment-generating function][mgf] (MGF).
```javascript
var chisquare = new ChiSquare( 2.0 );
var y = chisquare.mgf( 0.2 );
// returns ~1.667
```
#### ChiSquare.prototype.pdf( x )
Evaluates the [probability density function][pdf] (PDF).
```javascript
var chisquare = new ChiSquare( 2.0 );
var y = chisquare.pdf( 0.8 );
// returns ~0.335
```
#### ChiSquare.prototype.quantile( p )
Evaluates the [quantile function][quantile-function] at probability `p`.
```javascript
var chisquare = new ChiSquare( 2.0 );
var y = chisquare.quantile( 0.5 );
// returns ~1.386
y = chisquare.quantile( 1.9 );
// returns NaN
```
* * *
## Examples
```javascript
var ChiSquare = require( '@stdlib/stats-base-dists-chisquare-ctor' );
var chisquare = new ChiSquare( 2.0 );
var mu = chisquare.mean;
// returns 2.0
var mode = chisquare.mode;
// returns 0.0
var s2 = chisquare.variance;
// returns 4.0
var y = chisquare.cdf( 0.8 );
// returns ~0.33
```
* * *
## 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 © 2016-2024. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/stats-base-dists-chisquare-ctor.svg
[npm-url]: https://npmjs.org/package/@stdlib/stats-base-dists-chisquare-ctor
[test-image]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-base-dists-chisquare-ctor/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/stats-base-dists-chisquare-ctor?branch=main
[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im
[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-chisquare-ctor/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-ctor/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-dists-chisquare-ctor/main/LICENSE
[chisquare-distribution]: https://en.wikipedia.org/wiki/Chi-squared_distribution
[cdf]: https://en.wikipedia.org/wiki/Cumulative_distribution_function
[mgf]: https://en.wikipedia.org/wiki/Moment-generating_function
[pdf]: https://en.wikipedia.org/wiki/Probability_density_function
[quantile-function]: https://en.wikipedia.org/wiki/Quantile_function
[entropy]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29
[expected-value]: https://en.wikipedia.org/wiki/Expected_value
[kurtosis]: https://en.wikipedia.org/wiki/Kurtosis
[median]: https://en.wikipedia.org/wiki/Median
[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