@stdlib/stats/base/dists/degenerate/ctor/README.md

Standard library statistical functions.

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# Degenerate

> Degenerate distribution constructor.

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## Usage

```javascript
var Degenerate = require( '@stdlib/stats/base/dists/degenerate/ctor' );
```

#### Degenerate( \[mu] )

Returns a [Degenerate][degenerate-distribution] distribution object.

```javascript
var degenerate = new Degenerate();

var mean = degenerate.mean;
// returns 0.0
```

By default, `mu = 0.0`. To create a distribution having a different mean value `mu`, provide a parameter value.

```javascript
var degenerate = new Degenerate( 20.0 );

var mean = degenerate.mean;
// returns 20.0
```

* * *

## degenerate

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

### Writable Properties

#### degenerate.mu

Constant value of the distribution.

```javascript
var degenerate = new Degenerate( 2.0 );

var mu = degenerate.mu;
// returns 2.0

degenerate.mu = -2.0;

mu = degenerate.mu;
// returns -2.0
```

* * *

### Computed Properties

#### Degenerate.prototype.entropy

Returns the [differential entropy][entropy].

```javascript
var degenerate = new Degenerate( 4.0 );

var entropy = degenerate.entropy;
// returns 0.0
```

#### Degenerate.prototype.mean

Returns the [mean][expected-value].

```javascript
var degenerate = new Degenerate( 10.0 );

var mu = degenerate.mean;
// returns 10.0
```

#### Degenerate.prototype.median

Returns the [median][median].

```javascript
var degenerate = new Degenerate( 10.0 );

var median = degenerate.median;
// returns 10.0
```

#### Degenerate.prototype.mode

Returns the [mode][mode].

```javascript
var degenerate = new Degenerate( 10.0 );

var mode = degenerate.mode;
// returns 10.0
```

#### Degenerate.prototype.stdev

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

```javascript
var degenerate = new Degenerate( 4.0 );

var s = degenerate.stdev;
// returns 0.0
```

#### Degenerate.prototype.variance

Returns the [variance][variance].

```javascript
var degenerate = new Degenerate( 4.0 );

var s2 = degenerate.variance;
// returns 0.0
```

* * *

### Methods

#### Degenerate.prototype.cdf( x )

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

```javascript
var degenerate = new Degenerate( 0.2 );

var y = degenerate.cdf( 0.5 );
// returns 1.0
```

#### Degenerate.prototype.logcdf( x )

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

```javascript
var degenerate = new Degenerate( 0.2 );

var y = degenerate.logcdf( 0.5 );
// returns 0.0
```

#### Degenerate.prototype.logpdf( x )

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

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.logpdf( 9.0 );
// returns -Infinity

y = degenerate.logpdf( 10.0 );
// returns Infinity
```

#### Degenerate.prototype.logpmf( x )

Evaluates the natural logarithm of the [probability mass function][pmf] (logPMF).

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.logpmf( 9.0 );
// returns -Infinity

y = degenerate.logpmf( 10.0 );
// returns 0.0
```

#### Degenerate.prototype.mgf( t )

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

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.mgf( 0.1 );
// returns ~2.718
```

#### Degenerate.prototype.pdf( x )

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

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.pdf( 2.0 );
// returns 0.0

y = degenerate.pdf( 10.0 );
// returns +Infinity
```

#### Degenerate.prototype.pmf( x )

Evaluates the [probability mass function][pmf] (PMF).

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.pmf( 2.0 );
// returns 0.0

y = degenerate.pmf( 10.0 );
// returns 1.0
```

#### Degenerate.prototype.quantile( p )

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

```javascript
var degenerate = new Degenerate( 10.0 );

var y = degenerate.quantile( 0.5 );
// returns 10.0

y = degenerate.quantile( 0.9 );
// returns 10.0
```

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* * *

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## Examples

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```javascript
var Degenerate = require( '@stdlib/stats/base/dists/degenerate/ctor' );

var degenerate = new Degenerate( 0.5 );

var mu = degenerate.mean;
// returns 0.5

var s2 = degenerate.variance;
// returns 0.0

var y = degenerate.cdf( 2.0 );
// returns 1.0
```

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[degenerate-distribution]: https://en.wikipedia.org/wiki/Degenerate_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

[pmf]: https://en.wikipedia.org/wiki/Probability_mass_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

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

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

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

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

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