# @stdlib/stats-base-dists-chisquare-entropy

0.2.1 • Public • Published

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# Entropy

Chi-squared distribution differential entropy.

The differential entropy (in nats) for a chi-squared random variable is

where k > 0 is the degrees of freedom.

## Installation

npm install @stdlib/stats-base-dists-chisquare-entropy

## Usage

var entropy = require( '@stdlib/stats-base-dists-chisquare-entropy' );

#### entropy( k )

Returns the differential entropy of a chi-squared distribution with degrees of freedom k (in nats).

var v = entropy( 9.0 );
// returns ~2.786

v = entropy( 0.5 );
// returns ~-0.939

If provided k <= 0, the function returns NaN.

var v = entropy( -1.0 );
// returns NaN

## Examples

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

var k;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
k = randu() * 20.0;
v = entropy( k );
console.log( 'k: %d, entropy(X,k): %d', k.toFixed( 4 ), v.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.

## Package Sidebar

### Install

npm i @stdlib/stats-base-dists-chisquare-entropy

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