# atan2
> Compute the angle in the plane (in radians) between the positive x-axis and the ray from `(0,0)` to the point `(x,y)`.
## Usage
```javascript
var atan2 = require( '@stdlib/math/base/special/atan2' );
```
#### atan2( y, x )
Computes the angle in the plane (in radians) between the positive x-axis and the ray from `(0,0)` to the point `(x,y)`.
```javascript
var v = atan2( 2.0, 2.0 ); // => atan(1.0)
// returns ~0.785
v = atan2( 6.0, 2.0 ); // => atan(3.0)
// returns ~1.249
v = atan2( -1.0, -1.0 ); // => atan(1.0) - π
// returns ~-2.356
v = atan2( 3.0, 0.0 ); // => π/2
// returns ~1.571
v = atan2( -2.0, 0.0 ); // => -π/2
// returns ~-1.571
v = atan2( 0.0, 0.0 );
// returns 0.0
v = atan2( 3.0, NaN );
// returns NaN
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var atan2 = require( '@stdlib/math/base/special/atan2' );
var y;
var x;
var i;
for ( i = 0; i < 100; i++ ) {
y = randu() * 100.0;
x = randu() * 100.0;
console.log( 'y: %d, \t x: %d, \t atan2(y,x): %d', y.toFixed( 4 ), x.toFixed( 4 ), atan2( y, x ).toFixed( 4 ) );
}
```