# iterCospi
> Create an [iterator][mdn-iterator-protocol] which computes the [cosine][@stdlib/math/base/special/cospi] of each iterated value times π.
## Usage
```javascript
var iterCospi = require( '@stdlib/math/iter/special/cospi' );
```
#### iterCospi( iterator )
Returns an [iterator][mdn-iterator-protocol] which computes the [cosine][@stdlib/math/base/special/cospi] of each iterated value times π.
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var src = [ 0.0, 0.5, 0.1 ];
var it = iterCospi( array2iterator( src ) );
// returns
## Notes
- Computes `cos(πx)` more accurately than `cos(pi*x)`, especially for large `x`.
- 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 randu = require( '@stdlib/random/iter/randu' );
var iterCospi = require( '@stdlib/math/iter/special/cospi' );
// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234,
'iter': 10
});
// Create an iterator which consumes the pseudorandom number iterator:
var it = iterCospi( 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/cospi]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/cospi