Chi-squared distribution.
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> Chi-squared distribution.
``bash`
npm install @stdlib/stats-base-dists-chisquare
`javascript`
var chisquare = require( '@stdlib/stats-base-dists-chisquare' );
#### chisquare
Chi-squared distribution.
`javascript`
var dist = chisquare;
// returns {...}
The namespace contains the following distribution functions:
- [cdf( x, k )][@stdlib/stats/base/dists/chisquare/cdf]: Chi-squared distribution cumulative distribution function.
- [logpdf( x, k )][@stdlib/stats/base/dists/chisquare/logpdf]: evaluate the natural logarithm of the probability density function (PDF) for a chi-squared distribution.
- [mgf( t, k )][@stdlib/stats/base/dists/chisquare/mgf]: Chi-squared distribution moment-generating function (MGF).
- [pdf( x, k )][@stdlib/stats/base/dists/chisquare/pdf]: Chi-squared distribution probability density function (PDF).
- [quantile( p, k )][@stdlib/stats/base/dists/chisquare/quantile]: Chi-squared distribution quantile function.
The namespace contains the following functions for calculating distribution properties:
- [entropy( k )][@stdlib/stats/base/dists/chisquare/entropy]: Chi-squared distribution differential entropy.
- [kurtosis( k )][@stdlib/stats/base/dists/chisquare/kurtosis]: Chi-squared distribution excess kurtosis.
- [mean( k )][@stdlib/stats/base/dists/chisquare/mean]: Chi-squared distribution expected value.
- [median( k )][@stdlib/stats/base/dists/chisquare/median]: Chi-squared distribution median.
- [mode( k )][@stdlib/stats/base/dists/chisquare/mode]: Chi-squared distribution mode.
- [skewness( k )][@stdlib/stats/base/dists/chisquare/skewness]: Chi-squared distribution skewness.
- [stdev( k )][@stdlib/stats/base/dists/chisquare/stdev]: Chi-squared distribution standard deviation.
- [variance( k )][@stdlib/stats/base/dists/chisquare/variance]: Chi-squared distribution variance.
The namespace contains a constructor function for creating a [Chi-squared][chisquare-distribution] distribution object.
- [ChiSquare( [k] )][@stdlib/stats/base/dists/chisquare/ctor]: Chi-squared distribution constructor.
`javascript
var ChiSquare = require( '@stdlib/stats-base-dists-chisquare' ).ChiSquare;
var dist = new ChiSquare( 4.0 );
var mu = dist.mean;
// returns 4.0
`
`javascript
var roundn = require( '@stdlib/math-base-special-roundn' );
var chisquare = require( '@stdlib/stats-base-dists-chisquare' );
// Define degrees of freedom:
var k = 5.0;
// Calculate distribution properties:
console.log( 'Mean: %d', chisquare.mean( k ) );
console.log( 'Median: %d', roundn( chisquare.median( k ), -4 ) );
console.log( 'Mode: %d', chisquare.mode( k ) );
console.log( 'Variance: %d', chisquare.variance( k ) );
console.log( 'Standard Deviation: %d', roundn( chisquare.stdev( k ), -4 ) );
console.log( 'Skewness: %d', roundn( chisquare.skewness( k ), -4 ) );
console.log( 'Excess Kurtosis: %d', roundn( chisquare.kurtosis( k ), -4 ) );
console.log( 'Entropy: %d', roundn( chisquare.entropy( k ), -4 ) );
// Evaluate probability functions:
var x = 3.0;
console.log( '\nEvaluating at x = %d', x );
console.log( 'PDF: %d', roundn( chisquare.pdf( x, k ), -4 ) );
console.log( 'logPDF: %d', roundn( chisquare.logpdf( x, k ), -4 ) );
console.log( 'CDF: %d', roundn( chisquare.cdf( x, k ), -4 ) );
// Calculate quantiles:
var p = 0.7;
console.log( '\nQuantile at p = %d: %d', p, roundn( chisquare.quantile( p, k ), -4 ) );
// Evaluate moment-generating function:
var t = 0.1;
console.log( 'MGF at t = %d: %d', t, roundn( chisquare.mgf( t, k ), -4 ) );
`
*
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].
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---
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[deno-url]: https://github.com/stdlib-js/stats-base-dists-chisquare/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-base-dists-chisquare/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-base-dists-chisquare/tree/esm
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-dists-chisquare/main/LICENSE
[chisquare-distribution]: https://en.wikipedia.org/wiki/Chi-squared_distribution
[@stdlib/stats/base/dists/chisquare/ctor]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-ctor
[@stdlib/stats/base/dists/chisquare/entropy]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-entropy
[@stdlib/stats/base/dists/chisquare/kurtosis]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-kurtosis
[@stdlib/stats/base/dists/chisquare/mean]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-mean
[@stdlib/stats/base/dists/chisquare/median]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-median
[@stdlib/stats/base/dists/chisquare/mode]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-mode
[@stdlib/stats/base/dists/chisquare/skewness]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-skewness
[@stdlib/stats/base/dists/chisquare/stdev]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-stdev
[@stdlib/stats/base/dists/chisquare/variance]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-variance
[@stdlib/stats/base/dists/chisquare/cdf]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-cdf
[@stdlib/stats/base/dists/chisquare/logpdf]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-logpdf
[@stdlib/stats/base/dists/chisquare/mgf]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-mgf
[@stdlib/stats/base/dists/chisquare/pdf]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-pdf
[@stdlib/stats/base/dists/chisquare/quantile]: https://www.npmjs.com/package/@stdlib/stats-base-dists-chisquare-quantile