# iterMap2
> Create an [iterator][mdn-iterator-protocol] which invokes a binary function accepting numeric arguments for each iterated value.
## Usage
```javascript
var iterMap2 = require( '@stdlib/math/iter/tools/map2' );
```
#### iterMap2( iter0, iter1, fcn\[, options] )
Returns an [iterator][mdn-iterator-protocol] which invokes a binary `function` accepting numeric arguments for each iterated value.
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var copysign = require( '@stdlib/math/base/special/copysign' );
var it1 = array2iterator( [ 1.0, 2.0, 3.0, 4.0 ] );
var it2 = array2iterator( [ 1.0, -1.0, -1.0, 1.0 ] );
var it = iterMap2( it1, it2, copysign );
// 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** 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 uniform = require( '@stdlib/random/iter/uniform' );
var copysign = require( '@stdlib/math/base/special/copysign' );
var iterMap2 = require( '@stdlib/math/iter/tools/map2' );
// Create seeded iterators for generating pseudorandom numbers:
var rand1 = randu({
'seed': 1234,
'iter': 10
});
var rand2 = uniform( -1.0, 1.0, {
'seed': 1234,
'iter': 10
});
// Create an iterator which consumes the pseudorandom number iterators:
var it = iterMap2( rand1, rand2, copysign );
// 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