# Arccovercosine
> Compute the [inverse coversed cosine][inverse-coversed-cosine].
The [inverse coversed cosine][inverse-coversed-cosine] is defined as
## Usage
```javascript
var acovercos = require( '@stdlib/math/base/special/acovercos' );
```
#### acovercos( x )
Computes the [inverse coversed cosine][inverse-coversed-cosine].
```javascript
var v = acovercos( 0.0 );
// returns ~1.5708
v = acovercos( -3.141592653589793/2.0 );
// returns ~-0.6075
v = acovercos( -3.141592653589793/6.0 );
// returns ~0.4966
```
If `x < -2`, `x > 0`, or `x` is `NaN`, the function returns `NaN`.
```javascript
var v = acovercos( 1.0 );
// returns NaN
v = acovercos( -3.14 );
// returns NaN
v = acovercos( NaN );
// returns NaN
```
## Examples
```javascript
var linspace = require( '@stdlib/array/linspace' );
var acovercos = require( '@stdlib/math/base/special/acovercos' );
var x = linspace( -2.0, 0.0, 100 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( acovercos( x[ i ] ) );
}
```
[inverse-coversed-cosine]: https://en.wikipedia.org/wiki/Versine
