# itercuhmean
> Create an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [harmonic mean][harmonic-mean].
The [harmonic mean][harmonic-mean] of positive real numbers `x_0, x_1, ..., x_{n-1}` is defined as
## Usage
```javascript
var itercuhmean = require( '@stdlib/stats/iter/cuhmean' );
```
#### itercuhmean( iterator )
Returns an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [harmonic mean][harmonic-mean].
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0, 7.0, 5.0 ] );
var it = itercuhmean( arr );
var v = it.next().value;
// returns 2.0
v = it.next().value;
// returns ~1.33
v = it.next().value;
// returns ~1.64
v = it.next().value;
// returns ~2.02
v = it.next().value;
// returns ~2.30
```
## Notes
- If an iterated value is non-numeric (including `NaN`), the function returns `NaN` for **all** future iterations. If non-numeric 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 itercuhmean = require( '@stdlib/stats/iter/cuhmean' );
// 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 harmonic mean:
var it = itercuhmean( rand );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( typeof v.value === 'number' ) {
console.log( 'hmean: %d', v.value );
}
if ( v.done ) {
break;
}
}
```
[harmonic-mean]: https://en.wikipedia.org/wiki/Harmonic_mean
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
