npm package: @stdlib/stats-base-dists-logistic-ctor
Description: Logistic distribution constructor.
Author: The Stdlib Authors
Latest version: 0.2.3

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# Logistic

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> Logistic distribution constructor.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-base-dists-logistic-ctor
```

</section>

<section class="usage">

## Usage

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

#### Logistic( \[mu, s] )

Returns a [logistic][logistic-distribution] distribution object.

```javascript
var logistic = new Logistic();

var mu = logistic.mean;
// returns 0.0
```

By default, `mu = 0.0` and `s = 1.0`. To create a distribution having a different `mu` (location parameter) and `s` (scale parameter), provide the corresponding arguments.

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var mu = logistic.mean;
// returns 2.0
```

* * *

## logistic

A [logistic][logistic-distribution] distribution object has the following properties and methods...

### Writable Properties

#### logistic.mu

Location parameter of the distribution.

```javascript
var logistic = new Logistic();

var mu = logistic.mu;
// returns 0.0

logistic.mu = 3.0;

mu = logistic.mu;
// returns 3.0
```

#### logistic.s

Scale parameter of the distribution. `s` **must** be a positive number.

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var s = logistic.s;
// returns 4.0

logistic.s = 3.0;

s = logistic.s;
// returns 3.0
```

* * *

### Computed Properties

#### Logistic.prototype.entropy

Returns the [differential entropy][entropy].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var entropy = logistic.entropy;
// returns ~4.485
```

#### Logistic.prototype.kurtosis

Returns the [excess kurtosis][kurtosis].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var kurtosis = logistic.kurtosis;
// returns 1.2
```

#### Logistic.prototype.mean

Returns the [expected value][expected-value].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var mu = logistic.mean;
// returns 4.0
```

#### Logistic.prototype.median

Returns the [median][median].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var median = logistic.median;
// returns 4.0
```

#### Logistic.prototype.mode

Returns the [mode][mode].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var mode = logistic.mode;
// returns 4.0
```

#### Logistic.prototype.skewness

Returns the [skewness][skewness].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var skewness = logistic.skewness;
// returns 0.0
```

#### Logistic.prototype.stdev

Returns the [standard deviation][standard-deviation].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var s = logistic.stdev;
// returns ~21.766
```

#### Logistic.prototype.variance

Returns the [variance][variance].

```javascript
var logistic = new Logistic( 4.0, 12.0 );

var s2 = logistic.variance;
// returns ~473.741
```

* * *

### Methods

#### Logistic.prototype.cdf( x )

Evaluates the [cumulative distribution function][cdf] (CDF).

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.cdf( 0.5 );
// returns ~0.407
```

#### Logistic.prototype.logcdf( x )

Evaluates the natural logarithm of the [cumulative distribution function][cdf] (CDF).

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.logcdf( 2.0 );
// returns ~-0.693
```

#### Logistic.prototype.logpdf( x )

Evaluates the natural logarithm of the [probability density function][pdf] (PDF).

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.logpdf( 0.8 );
// returns ~-2.795
```

#### Logistic.prototype.mgf( t )

Evaluates the [moment-generating function][mgf] (MGF).

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.mgf( 0.2 );
// returns ~6.379
```

#### Logistic.prototype.pdf( x )

Evaluates the [probability density function][pdf] (PDF).

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.pdf( 2.0 );
// returns 0.0625
```

#### Logistic.prototype.quantile( p )

Evaluates the [quantile function][quantile-function] at probability `p`.

```javascript
var logistic = new Logistic( 2.0, 4.0 );

var y = logistic.quantile( 0.5 );
// returns 2.0

y = logistic.quantile( 1.9 );
// returns NaN
```

</section>

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<section class="notes">

</section>

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<!-- Package usage examples. -->

* * *

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

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

var logistic = new Logistic( 2.0, 4.0 );

var mean = logistic.mean;
// returns 2.0

var median = logistic.median;
// returns 2.0

var s2 = logistic.variance;
// returns ~52.638

var y = logistic.cdf( 0.8 );
// returns ~0.426
```

</section>

<!-- /.examples -->

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<section class="main-repo" >

* * *

## 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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-dists-logistic-ctor/main/LICENSE

[logistic-distribution]: https://en.wikipedia.org/wiki/Logistic_distribution

[cdf]: https://en.wikipedia.org/wiki/Cumulative_distribution_function

[mgf]: https://en.wikipedia.org/wiki/Moment-generating_function

[pdf]: https://en.wikipedia.org/wiki/Probability_density_function

[quantile-function]: https://en.wikipedia.org/wiki/Quantile_function

[entropy]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29

[expected-value]: https://en.wikipedia.org/wiki/Expected_value

[kurtosis]: https://en.wikipedia.org/wiki/Kurtosis

[median]: https://en.wikipedia.org/wiki/Median

[mode]: https://en.wikipedia.org/wiki/Mode_%28statistics%29

[skewness]: https://en.wikipedia.org/wiki/Skewness

[standard-deviation]: https://en.wikipedia.org/wiki/Standard_deviation

[variance]: https://en.wikipedia.org/wiki/Variance

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