npm package: @stdlib/stats-iter-cuhmean
Description: Create an iterator which iteratively computes a cumulative harmonic mean.
Author: The Stdlib Authors
Latest version: 0.2.3

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# itercuhmean

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

> Create an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [harmonic mean][harmonic-mean].

<section class="intro">

The [harmonic mean][harmonic-mean] of positive real numbers `x_0, x_1, ..., x_{n-1}` is defined as

<!-- <equation class="equation" label="eq:harmonic_mean" align="center" raw="\begin{align}H &= \frac{n}{\frac{1}{x_0} + \frac{1}{x_1} + \cdots + \frac{1}{x_{n-1}}} \\ &= \frac{n}{\displaystyle\sum_{i=0}^{n-1} \frac{1}{x_i}} \\ &= \biggl( \frac{\displaystyle\sum_{i=0}^{n-1} \frac{1}{x_i}}{n} \biggr)^{-1}\end{align}" alt="Equation for the harmonic mean."> -->

<div class="equation" align="center" data-raw-text="\begin{align}H &amp;= \frac{n}{\frac{1}{x_0} + \frac{1}{x_1} + \cdots + \frac{1}{x_{n-1}}} \\ &amp;= \frac{n}{\displaystyle\sum_{i=0}^{n-1} \frac{1}{x_i}} \\ &amp;= \biggl( \frac{\displaystyle\sum_{i=0}^{n-1} \frac{1}{x_i}}{n} \biggr)^{-1}\end{align}" data-equation="eq:harmonic_mean">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@c00986cca2dbfac62b50df74d56662f485b6d4e5/lib/node_modules/@stdlib/stats/iter/cuhmean/docs/img/equation_harmonic_mean.svg" alt="Equation for the harmonic mean.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-iter-cuhmean
```

</section>

<section class="usage">

## Usage

```javascript
var itercuhmean = require( '@stdlib/stats-iter-cuhmean' );
```

#### itercuhmean( iterator )

Returns an [iterator][mdn-iterator-protocol] which iteratively computes a cumulative [harmonic mean][harmonic-mean].

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

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

var v = it.next().value;
// returns 2.0

v = it.next().value;
// returns ~1.33

v = it.next().value;
// returns ~1.64

v = it.next().value;
// returns ~2.02

v = it.next().value;
// returns ~2.30
```

</section>

<!-- /.usage -->

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

<section class="notes">

## Notes

-   If an iterated value is non-numeric (including `NaN`), the function returns `NaN` for **all** future iterations. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles such values accordingly.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var runif = require( '@stdlib/random-iter-uniform' );
var itercuhmean = require( '@stdlib/stats-iter-cuhmean' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( 0.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a cumulative harmonic mean:
var it = itercuhmean( rand );

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

</section>

<!-- /.examples -->

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<section class="references">

</section>

<!-- /.references -->

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/stats-iter/cugmean`][@stdlib/stats/iter/cugmean]</span><span class="delimiter">: </span><span class="description">create an iterator which iteratively computes a cumulative geometric mean.</span>
-   <span class="package-name">[`@stdlib/stats-iter/cumean`][@stdlib/stats/iter/cumean]</span><span class="delimiter">: </span><span class="description">create an iterator which iteratively computes a cumulative arithmetic mean.</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].

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[stdlib]: https://github.com/stdlib-js/stdlib

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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/stats-iter-cuhmean/tree/deno
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-iter-cuhmean/main/LICENSE

[harmonic-mean]: https://en.wikipedia.org/wiki/Harmonic_mean

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

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

[@stdlib/stats/iter/cugmean]: https://www.npmjs.com/package/@stdlib/stats-iter-cugmean

[@stdlib/stats/iter/cumean]: https://www.npmjs.com/package/@stdlib/stats-iter-cumean

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</section>

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