# iterAdd
> Create an [iterator][mdn-iterator-protocol] which performs element-wise addition of two or more [iterators][mdn-iterator-protocol].
## Usage
```javascript
var iterAdd = require( '@stdlib/math/iter/ops/add' );
```
#### iterAdd( iter0, ...iterator )
Returns an [iterator][mdn-iterator-protocol] which performs element-wise addition of two or more [iterators][mdn-iterator-protocol].
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var it1 = array2iterator( [ 1.0, 2.0 ] );
var it2 = array2iterator( [ 3.0, 4.0 ] );
var it = iterAdd( it1, it2 );
// returns
## Notes
- 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.
- The length of the returned [iterator][mdn-iterator-protocol] is equal to the length of the shortest provided [iterator][mdn-iterator-protocol]. In other words, the returned [iterator][mdn-iterator-protocol] ends once **one** of the provided [iterators][mdn-iterator-protocol] ends.
- If an environment supports `Symbol.iterator` **and** provided [iterators][mdn-iterator-protocol] are iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
## Examples
```javascript
var iterSineWave = require( '@stdlib/simulate/iter/sine-wave' );
var iterAdd = require( '@stdlib/math/iter/ops/add' );
// Create an iterator which generates a sine wave:
var sine1 = iterSineWave({
'period': 50,
'offset': 0,
'iter': 100
});
// Create another iterator which generates a higher frequency sine wave:
var sine2 = iterSineWave({
'period': 10,
'offset': 0,
'iter': 100
});
// Create an iterator which adds the two waveforms:
var it = iterAdd( sine1, sine2 );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( v.done ) {
break;
}
console.log( v.value );
}
```
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol