npm package: @stdlib/stats-incr-nansum
Description: Compute a sum incrementally, ignoring NaN values.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
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</details>

# incrnansum

[![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 incrementally, ignoring `NaN` values.

<section class="intro">

The sum is defined as

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

<div class="equation" align="center" data-raw-text="s = \sum_{i=0}^{n-1} x_i" data-equation="eq:sum">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@eb48b7659e2110aba9fb9c120942cee2e0c4bf5c/lib/node_modules/@stdlib/stats/incr/nansum/docs/img/equation_sum.svg" alt="Equation for the sum.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

```javascript
var incrnansum = require( '@stdlib/stats-incr-nansum' );
```

#### incrnansum()

Returns an accumulator `function` which incrementally computes a sum, ignoring `NaN` values.

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

#### 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 = incrnansum();

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

sum = accumulator( 1.0 );
// returns 3.0

sum = accumulator( NaN );
// returns 3.0

sum = accumulator( 3.0 );
// returns 6.0

sum = accumulator();
// returns 6.0
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Input values are **not** type checked. 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 incrnansum = require( '@stdlib/stats-incr-nansum' );

var accumulator;
var v;
var i;

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

// For each simulated datum, update the sum...
for ( i = 0; i < 100; i++ ) {
    if ( randu() < 0.2 ) {
        v = NaN;
    } else {
        v = randu() * 100.0;
    }
    accumulator( v );
}
console.log( accumulator() );
```

</section>

<!-- /.examples -->

<section class="references">

</section>

<!-- /.references -->

<!-- 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/nansumabs`][@stdlib/stats/incr/nansumabs]</span><span class="delimiter">: </span><span class="description">compute a sum of absolute values incrementally, ignoring NaN values.</span>
-   <span class="package-name">[`@stdlib/stats-incr/sum`][@stdlib/stats/incr/sum]</span><span class="delimiter">: </span><span class="description">compute a sum incrementally.</span>

</section>

<!-- /.related -->

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<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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[umd]: https://github.com/umdjs/umd
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<!-- <related-links> -->

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

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

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</section>

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