npm package: @stdlib/stats-incr-sumabs2
Description: Compute a sum of squared absolute values incrementally.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
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    About stdlib...
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  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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# incrsumabs2

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Compute a sum of squared absolute values incrementally.

<section class="intro">

The sum of squared absolute values is defined as

<!-- <equation class="equation" label="eq:sum_squared_absolute_values" align="center" raw="s = \sum_{i=0}^{n-1} x_i^2" alt="Equation for the sum of squared absolute values."> -->

<div class="equation" align="center" data-raw-text="s = \sum_{i=0}^{n-1} x_i^2" data-equation="eq:sum_squared_absolute_values">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@5278c8e8327430b39dd12985f7dac6d5f8033d34/lib/node_modules/@stdlib/stats/incr/sumabs2/docs/img/equation_sum_squared_absolute_values.svg" alt="Equation for the sum of squared absolute values.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-incr-sumabs2
```

</section>

<section class="usage">

## Usage

```javascript
var incrsumabs2 = require( '@stdlib/stats-incr-sumabs2' );
```

#### incrsumabs2()

Returns an accumulator `function` which incrementally computes a sum of squared absolute values.

```javascript
var accumulator = incrsumabs2();
```

#### accumulator( \[x] )

If provided an input value `x`, the accumulator function returns an updated sum. If not provided an input value `x`, the accumulator function returns the current sum.

```javascript
var accumulator = incrsumabs2();

var sum = accumulator( 2.0 );
// returns 4.0

sum = accumulator( -1.0 );
// returns 5.0

sum = accumulator( -3.0 );
// returns 14.0

sum = accumulator();
// returns 14.0
```

</section>

<!-- /.usage -->

<section class="notes">

## 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.
-   For long running accumulations or accumulations of large numbers, care should be taken to prevent overflow.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random-base-randu' );
var incrsumabs2 = require( '@stdlib/stats-incr-sumabs2' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrsumabs2();

// For each simulated datum, update the sum...
for ( i = 0; i < 100; i++ ) {
    v = ( randu()*100.0 ) - 50.0;
    accumulator( v );
}
console.log( accumulator() );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/stats-incr/meanabs2`][@stdlib/stats/incr/meanabs2]</span><span class="delimiter">: </span><span class="description">compute an arithmetic mean of squared absolute values incrementally.</span>
-   <span class="package-name">[`@stdlib/stats-incr/msumabs2`][@stdlib/stats/incr/msumabs2]</span><span class="delimiter">: </span><span class="description">compute a moving sum of squared absolute values incrementally.</span>
-   <span class="package-name">[`@stdlib/stats-incr/sumabs`][@stdlib/stats/incr/sumabs]</span><span class="delimiter">: </span><span class="description">compute a sum of absolute values incrementally.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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<!-- <related-links> -->

[@stdlib/stats/incr/meanabs2]: https://www.npmjs.com/package/@stdlib/stats-incr-meanabs2

[@stdlib/stats/incr/msumabs2]: https://www.npmjs.com/package/@stdlib/stats-incr-msumabs2

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