# itercugmean
> Create an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [geometric mean][geometric-mean].
The [geometric mean][geometric-mean] is defined as the nth root of a product of _n_ numbers.
## Usage
```javascript
var itercugmean = require( '@stdlib/stats/iter/cugmean' );
```
#### itercugmean( iterator )
Returns an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [geometric mean][geometric-mean].
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0, 7.0, 5.0 ] );
var it = itercugmean( arr );
var v = it.next().value;
// returns 2.0
v = it.next().value;
// returns ~1.41
v = it.next().value;
// returns ~1.82
v = it.next().value;
// returns ~2.55
v = it.next().value;
// returns ~2.91
```
## Notes
- If an iterated value is non-numeric (including `NaN`) or negative, the function returns `NaN` for **all** future iterations. If non-numeric and/or negative iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles such values accordingly.
## Examples
```javascript
var runif = require( '@stdlib/random/iter/uniform' );
var itercugmean = require( '@stdlib/stats/iter/cugmean' );
// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( 0.0, 10.0, {
'seed': 1234,
'iter': 100
});
// Create an iterator for iteratively computing a cumulative geometric mean:
var it = itercugmean( rand );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( typeof v.value === 'number' ) {
console.log( 'gmean: %d', v.value );
}
if ( v.done ) {
break;
}
}
```
[geometric-mean]: https://en.wikipedia.org/wiki/Geometric_mean
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
