# iterstdev
> Compute the [corrected sample standard deviation][sample-stdev] over all [iterated][mdn-iterator-protocol] values.
The [corrected sample standard deviation][sample-stdev] is defined as
## Usage
```javascript
var iterstdev = require( '@stdlib/stats/iter/stdev' );
```
#### iterstdev( iterator\[, mean] )
Computes the [corrected sample standard deviation][sample-stdev] over all [iterated][mdn-iterator-protocol] values.
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0 ] );
var s = iterstdev( arr );
// returns 1.0
```
If the mean is already known, provide a `mean` argument.
```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0 ] );
var s = iterstdev( arr, 2.0 );
// returns ~0.82
```
## 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.
## Examples
```javascript
var runif = require( '@stdlib/random/iter/uniform' );
var iterstdev = require( '@stdlib/stats/iter/stdev' );
// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
'seed': 1234,
'iter': 100
});
// Compute the corrected sample standard deviation:
var s = iterstdev( rand );
// returns
console.log( 'stdev: %d.', s );
```
[sample-stdev]: https://en.wikipedia.org/wiki/Standard_deviation
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
