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stdlib-js/stats-base-dists-rayleigh-skewness

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Skewness

NPM version Build Status Coverage Status

Rayleigh distribution skewness.

The skewness for a Rayleigh random variable is

$$\mathop{\mathrm{skew}}\left( X \right) = \frac{2{\sqrt{\pi }}(\pi -3)}{(4-\pi )^{3/2}}$$

where σ > 0 is the scale parameter.

Installation

npm install @stdlib/stats-base-dists-rayleigh-skewness

Alternatively,

  • To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
  • If you are using Deno, visit the deno branch (see README for usage intructions).
  • For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md 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

var skewness = require( '@stdlib/stats-base-dists-rayleigh-skewness' );

skewness( sigma )

Returns the skewness of a Rayleigh distribution with scale parameter sigma.

var y = skewness( 9.0 );
// returns ~0.631

y = skewness( 3.5 );
// returns ~0.631

If provided sigma < 0, the function returns NaN.

var y = skewness( -1.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var skewness = require( '@stdlib/stats-base-dists-rayleigh-skewness' );

var sigma;
var y;
var i;

for ( i = 0; i < 10; i++ ) {
    sigma = randu() * 20.0;
    y = skewness( sigma );
    console.log( 'σ: %d, skew(X,σ): %d', sigma.toFixed( 4 ), y.toFixed( 4 ) );
}

Notice

This package is part of 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, see the main project repository.

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License

See LICENSE.

Copyright

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