# Cosine
> Compute the [cosine][cosine] of a number.
## 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
```
## Examples
```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 ] ) );
}
```
[cosine]: https://en.wikipedia.org/wiki/Cosine