# iterAvercos
> Create an [iterator][mdn-iterator-protocol] which iteratively computes the [inverse versed cosine][@stdlib/math/base/special/avercos].
## Usage
```javascript
var iterAvercos = require( '@stdlib/math/iter/special/avercos' );
```
#### iterAvercos( iterator )
Returns an [iterator][mdn-iterator-protocol] which iteratively computes the [inverse versed cosine][@stdlib/math/base/special/avercos].
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var x = [ 0.0, -3.141592653589793/2.0, -3.141592653589793/6.0 ];
var it = iterAvercos( array2iterator( x ) );
// returns
## Notes
- The domain of inverse versed cosine is restricted to `[-2,0]`. If an iterated value is outside of the domain, the returned [iterator][mdn-iterator-protocol] returns `NaN`.
- If an iterated value is non-numeric (including `NaN`), the returned [iterator][mdn-iterator-protocol] returns `NaN`. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.
- If an environment supports `Symbol.iterator` **and** a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
## Examples
```javascript
var uniform = require( '@stdlib/random/iter/uniform' );
var iterAvercos = require( '@stdlib/math/iter/special/avercos' );
// Create a seeded iterator for generating pseudorandom numbers:
var rand = uniform( -2.0, 0.0, {
'seed': 1234,
'iter': 10
});
// Create an iterator which consumes the pseudorandom number iterator:
var it = iterAvercos( rand );
// Perform manual iteration...
var r;
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}
```
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
[@stdlib/math/base/special/avercos]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/avercos