Nighttime Possum Meandering

# npm

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

0.0.7 • Public • Published

# Entropy

F distribution differential entropy.

The differential entropy (in nats) for a F random variable is

where `d1` is the numerator degrees of freedom, `d2` is the denominator degrees of freedom, and `Γ` and `Ψ` denote the gamma and digamma functions, respectively.

## Installation

`npm install @stdlib/stats-base-dists-f-entropy`

## Usage

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

#### entropy( d1, d2 )

Returns the differential entropy of a F distribution with numerator degrees of freedom `d1` and denominator degrees of freedom `d2` (in nats).

```var v = entropy( 4.0, 7.0 );
// returns ~1.277

v = entropy( 4.0, 12.0 );
// returns ~1.12

v = entropy( 8.0, 2.0 );
// returns ~2.144```

If provided `NaN` as any argument, the function returns `NaN`.

```var v = entropy( NaN, 7.0 );
// returns NaN

v = entropy( 3.0, NaN );
// returns NaN```

If provided `d1 <= 0`, the function returns `NaN`.

```var v = entropy( 0.0, 2.0 );
// returns NaN

v = entropy( -1.0, 1.0 );
// returns NaN```

If provided `d2 <= 0`, the function returns `NaN`.

```var v = entropy( 3.0, 0.0 );
// returns NaN

v = entropy( 3.0, -1.0 );
// returns NaN```

## Examples

```var randu = require( '@stdlib/random-base-randu' );
var EPS = require( '@stdlib/constants-float64-eps' );
var entropy = require( '@stdlib/stats-base-dists-f-entropy' );

var d1;
var d2;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
d1 = ( randu()*10.0 ) + EPS;
d2 = ( randu()*10.0 ) + EPS;
v = entropy( d1, d2 );
console.log( 'd1: %d, d2: %d, h(X;d1,d2): %d', d1.toFixed( 4 ), d2.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.

### Install

`npm i @stdlib/stats-base-dists-f-entropy`

stdlib.io

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