# incrmeanabs2
> Compute an [arithmetic mean][arithmetic-mean] of squared absolute values incrementally.
The [arithmetic mean][arithmetic-mean] of squared absolute values is defined as
## Usage
```javascript
var incrmeanabs2 = require( '@stdlib/stats/incr/meanabs2' );
```
#### incrmeanabs2()
Returns an accumulator `function` which incrementally computes an [arithmetic mean][arithmetic-mean] of squared absolute values.
```javascript
var accumulator = incrmeanabs2();
```
#### accumulator( \[x] )
If provided an input value `x`, the accumulator function returns an updated mean. If not provided an input value `x`, the accumulator function returns the current mean.
```javascript
var accumulator = incrmeanabs2();
var m = accumulator( 2.0 );
// returns 4.0
m = accumulator( -1.0 );
// returns 2.5
m = accumulator( -3.0 );
// returns ~4.67
m = accumulator();
// returns ~4.67
```
## Notes
- Input values are **not** type checked. If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for **all** future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var incrmeanabs2 = require( '@stdlib/stats/incr/meanabs2' );
var accumulator;
var v;
var i;
// Initialize an accumulator:
accumulator = incrmeanabs2();
// For each simulated datum, update the mean...
for ( i = 0; i < 100; i++ ) {
v = ( randu()*100.0 ) - 50.0;
accumulator( v );
}
console.log( accumulator() );
```
[arithmetic-mean]: https://en.wikipedia.org/wiki/Arithmetic_mean
