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# gammaln

> [Natural logarithm][@stdlib/math/base/special/ln] of the [gamma][@stdlib/math/base/special/gamma] function.

<section class="usage">

## Usage

```javascript
var gammaln = require( '@stdlib/math/base/special/gammaln' );
```

#### gammaln( x )

Evaluates the [natural logarithm][@stdlib/math/base/special/ln] of the [gamma function][@stdlib/math/base/special/gamma].

```javascript
var v = gammaln( 2.0 );
// returns 0.0

v = gammaln( 1.0 );
// returns 0.0

v = gammaln( 4.0 );
// returns ~1.792

v = gammaln( -0.5 );
// returns ~1.266

v = gammaln( 0.5 );
// returns ~0.572

v = gammaln( 0.0 );
// returns Infinity

v = gammaln( NaN );
// returns NaN
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var linspace = require( '@stdlib/array/linspace' );
var gammaln = require( '@stdlib/math/base/special/gammaln' );

var x = linspace( -10.0, 10.0, 100 );
var v;
var i;

for ( i = 0; i < x.length; i++ ) {
    v = gammaln( x[ i ] );
    console.log( 'x: %d, f(x): %d', x[ i ], v );
}
```

</section>

<!-- /.examples -->

<section class="links">

[@stdlib/math/base/special/gamma]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/gamma

[@stdlib/math/base/special/ln]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/ln

</section>

<!-- /.links -->