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# Cosine

> Compute the [cosine][cosine] of a number.

<section class="usage">

## Usage

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

#### cos( x )

Computes the [cosine][cosine] of a `number` (in radians).

```javascript
var v = cos( 0.0 );
// returns 1.0

v = cos( 3.141592653589793/4.0 );
// returns ~0.707

v = cos( -3.141592653589793/6.0 );
// returns ~0.866

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

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var linspace = require( '@stdlib/array/linspace' );
var TWO_PI = require( '@stdlib/constants/float64/two-pi' );
var cos = require( '@stdlib/math/base/special/cos' );

var x = linspace( 0.0, TWO_PI, 100 );
var i;

for ( i = 0; i < x.length; i++ ) {
    console.log( cos( x[ i ] ) );
}
```

</section>

<!-- /.examples -->

<section class="links">

[cosine]: https://en.wikipedia.org/wiki/Cosine

</section>

<!-- /.links -->