# @stdlib/stats-base-dists-logistic-variance

0.2.1 • Public • Published

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# Variance

Logistic distribution variance.

The variance for a logistic random variable with location `μ` and scale `s > 0` is

## Installation

`npm install @stdlib/stats-base-dists-logistic-variance`

## Usage

`var variance = require( '@stdlib/stats-base-dists-logistic-variance' );`

#### variance( mu, s )

Returns the variance for a logistic distribution with location parameter `mu` and scale parameter `s`.

```var y = variance( 2.0, 1.0 );
// returns ~3.29

y = variance( 0.0, 1.0 );
// returns ~3.29

y = variance( -1.0, 4.0 );
// returns ~52.638```

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

```var y = variance( NaN, 1.0 );
// returns NaN

y = variance( 0.0, NaN );
// returns NaN```

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

```var y = variance( 0.0, 0.0 );
// returns NaN

y = variance( 0.0, -1.0 );
// returns NaN```

## Examples

```var randu = require( '@stdlib/random-base-randu' );
var variance = require( '@stdlib/stats-base-dists-logistic-variance' );

var mu;
var s;
var y;
var i;

for ( i = 0; i < 10; i++ ) {
mu = ( randu()*10.0 ) - 5.0;
s = randu() * 20.0;
y = variance( mu, s );
console.log( 'µ: %d, s: %d, Var(X;µ,s): %d', mu.toFixed( 4 ), s.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.

## Package Sidebar

### Install

`npm i @stdlib/stats-base-dists-logistic-variance`

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