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# itermmaxabs

> Create an [iterator][mdn-iterator-protocol] which iteratively computes a moving maximum absolute value.

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</section>

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<section class="usage">

## Usage

```javascript
var itermmaxabs = require( '@stdlib/stats/iter/mmaxabs' );
```

#### itermmaxabs( iterator, W )

Returns an [iterator][mdn-iterator-protocol] which iteratively computes a moving maximum absolute value. The `W` parameter defines the number of iterated values over which to compute the moving maximum absolute value.

```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );

var arr = array2iterator( [ 2.0, 1.0, 3.0, -7.0, -5.0 ] );
var it = itermmaxabs( arr, 3 );

// Fill the window...
var m = it.next().value; // [2.0]
// returns 2.0

m = it.next().value; // [2.0, 1.0]
// returns 2.0

m = it.next().value; // [2.0, 1.0, 3.0]
// returns 3.0

// Window begins sliding...
m = it.next().value; // [1.0, 3.0, -7.0]
// returns 7.0

m = it.next().value; // [3.0, -7.0, -5.0]
// returns 7.0
```

</section>

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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

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## Notes

-   If an iterated value is non-numeric (including `NaN`), the function returns `NaN` for **at least** `W-1` future invocations. 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.
-   As `W` values are needed to fill the window buffer, the first `W-1` returned values are calculated from smaller sample sizes. Until the window is full, each returned value is calculated from all previously iterated values.

</section>

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<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var runif = require( '@stdlib/random/iter/uniform' );
var itermmaxabs = require( '@stdlib/stats/iter/mmaxabs' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a moving maximum absolute value:
var it = itermmaxabs( rand, 3 );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( typeof v.value === 'number' ) {
        console.log( 'maxabs: %d', v.value );
    }
    if ( v.done ) {
        break;
    }
}
```

</section>

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<section class="links">

[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol

</section>

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