@stdlib/stats-base-dists-chisquare-variance
v0.3.1TypeScript
Chi-squared distribution variance.
0/weekUpdated 3 days agoApache-2.0Unpacked: 39.5 KB
Published by The Stdlib Authors
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About stdlib...
Variance
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> [Chi-squared][chisquare-distribution] distribution [variance][variance].
The [variance][variance] for a [chi-squared][chisquare-distribution] random variable is
where k >= 0 is the degrees of freedom.
Installation
``bash`
npm install @stdlib/stats-base-dists-chisquare-variance
Usage
`javascript`
var variance = require( '@stdlib/stats-base-dists-chisquare-variance' );
#### variance( k )
Returns the [variance][variance] of a [chi-squared][chisquare-distribution] distribution with degrees of freedom k.
`javascript
var v = variance( 9.0 );
// returns 18.0
v = variance( 0.5 );
// returns 1.0
`
If provided k < 0, the function returns NaN.
`javascript`
var v = variance( -1.0 );
// returns NaN
Examples
`javascript
var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var variance = require( '@stdlib/stats-base-dists-chisquare-variance' );
var opts = {
'dtype': 'float64'
};
var k = uniform( 10, 0.0, 20.0, opts );
logEachMap( 'k: %0.4f, Var(X;k): %0.4f', k, variance );
`
*
C APIs
$3
`c`
#include "stdlib/stats/base/dists/chisquare/variance.h"
#### stdlib_base_dists_chisquare_variance( k )
Returns the [variance][variance] of a [chi-squared][chisquare-distribution] distribution with degrees of freedom k.
`c`
double out = stdlib_base_dists_chisquare_variance( 9.0 );
// returns 18.0
The function accepts the following arguments:
- k: [in] double degrees of freedom.
`c`
double stdlib_base_dists_chisquare_variance( const double k );
$3
`c
#include "stdlib/stats/base/dists/chisquare/variance.h"
#include
#include
static double random_uniform( const double min, const double max ) {
double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
return min + ( v*(max-min) );
}
int main( void ) {
double k;
double y;
int i;
for ( i = 0; i < 25; i++ ) {
k = random_uniform( 0.0, 20.0 );
y = stdlib_base_dists_chisquare_variance( k );
printf( "k: %lf, Var(X;k): %lf\n", k, y );
}
}
`
*
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].
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[npm-url]: https://npmjs.org/package/@stdlib/stats-base-dists-chisquare-variance
[test-image]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/actions/workflows/test.yml/badge.svg?branch=v0.3.1
[test-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/actions/workflows/test.yml?query=branch:v0.3.1
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-base-dists-chisquare-variance/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/stats-base-dists-chisquare-variance?branch=main
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[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-variance/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-base-dists-chisquare-variance/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-dists-chisquare-variance/main/LICENSE
[chisquare-distribution]: https://en.wikipedia.org/wiki/Chi-squared_distribution
[variance]: https://en.wikipedia.org/wiki/Variance