# Tangent
> Evaluate the [tangent][tangent] of a number.
The [tangent][tangent] is defined as
## Usage
```javascript
var tan = require( '@stdlib/math/base/special/tan' );
```
#### tan( x )
Evaluates the [tangent][tangent] of a `number` (in radians).
```javascript
var v = tan( 0.0 );
// returns ~0.0
v = tan( -3.141592653589793/4.0 );
// returns ~-1.0
v = tan( 3.141592653589793/4.0 );
// returns ~1.0
v = tan( NaN );
// returns NaN
```
## Examples
```javascript
var linspace = require( '@stdlib/array/linspace' );
var PI = require( '@stdlib/constants/float64/pi' );
var tan = require( '@stdlib/math/base/special/tan' );
var x = linspace( -PI/2.0, PI/2.0, 100 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( tan( x[ i ] ) );
}
```
[tangent]: http://mathworld.wolfram.com/Tangent.html
