npm package: @stdlib/math-iter-special-gamma1pm1
Description: Create an iterator which computes `gamma(x+1) - 1` for each iterated value.
Author: The Stdlib Authors
Latest version: 0.2.3

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# iterGamma1pm1

[![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 computes [`gamma(x+1) - 1`][@stdlib/math/base/special/gamma1pm1] for each iterated value.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/math-iter-special-gamma1pm1
```

</section>

<section class="usage">

## Usage

```javascript
var iterGamma1pm1 = require( '@stdlib/math-iter-special-gamma1pm1' );
```

#### iterGamma1pm1( iterator )

Returns an [iterator][mdn-iterator-protocol] which iteratively computes [`gamma(x+1) - 1`][@stdlib/math/base/special/gamma1pm1] without cancellation errors for small `x`.

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

var it = iterGamma1pm1( array2iterator( [ 0.2, -8.5 ] ) );
// returns <Object>

var v = it.next().value;
// returns ~-0.082

v = it.next().value;
// returns ~-1.0

// ...
```

The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the following properties:

-   **next**: function which returns an [iterator][mdn-iterator-protocol] protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a `boolean` value indicating whether the iterator is finished.
-   **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.

</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 returned [iterator][mdn-iterator-protocol] returns `NaN`. 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.
-   If an environment supports `Symbol.iterator` **and** a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var uniform = require( '@stdlib/random-iter-uniform' );
var iterGamma1pm1 = require( '@stdlib/math-iter-special-gamma1pm1' );

// Create a seeded iterator for generating pseudorandom numbers:
var rand = uniform( -5.0, 5.0, {
    'seed': 1234,
    'iter': 10
});

// Create an iterator which consumes the pseudorandom number iterator:
var it = iterGamma1pm1( rand );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( v.done ) {
        break;
    }
    console.log( v.value );
}
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/math-base/special/gamma1pm1`][@stdlib/math/base/special/gamma1pm1]</span><span class="delimiter">: </span><span class="description">compute gamma(x+1) - 1.</span>
-   <span class="package-name">[`@stdlib/math-iter/special/gamma`][@stdlib/math/iter/special/gamma]</span><span class="delimiter">: </span><span class="description">create an iterator which evaluates the gamma function for each iterated value.</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>

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

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[@stdlib/math/base/special/gamma1pm1]: https://www.npmjs.com/package/@stdlib/math-base-special-gamma1pm1

[@stdlib/math/iter/special/gamma]: https://www.npmjs.com/package/@stdlib/math-iter-special-gamma

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