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# iterFactorial

> Create an [iterator][mdn-iterator-protocol] which iteratively evaluates the [factorial function][@stdlib/math/base/special/factorial].

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## Usage

```javascript
var iterFactorial = require( '@stdlib/math/iter/special/factorial' );
```

#### iterFactorial( iterator )

Returns an [iterator][mdn-iterator-protocol] which iteratively evaluates the [factorial function][@stdlib/math/base/special/factorial].

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

var it = iterFactorial( array2iterator( [ 3.0, -1.5, -0.5 ] ) );
// returns <Object>

var r = it.next().value;
// returns 6.0

r = it.next().value;
// returns ~-3.545

r = it.next().value;
// returns ~1.772

// ...
```

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.

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## 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.

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## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/iter/discrete-uniform' );
var iterFactorial = require( '@stdlib/math/iter/special/factorial' );

// Create a seeded iterator for generating pseudorandom numbers:
var rand = discreteUniform( 0, 171, {
    'seed': 1234,
    'iter': 10
});

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

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

</section>

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* * *

## See Also

-   <span class="package-name">[`@stdlib/math/base/special/factorial`][@stdlib/math/base/special/factorial]</span><span class="delimiter">: </span><span class="description">evaluate a factorial.</span>
-   <span class="package-name">[`@stdlib/math/iter/special/factorialln`][@stdlib/math/iter/special/factorialln]</span><span class="delimiter">: </span><span class="description">create an iterator which evaluates the natural logarithm of the factorial function for each iterated value.</span>

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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/factorial]: https://github.com/stdlib-js/math/tree/main/base/special/factorial

[@stdlib/math/iter/special/factorialln]: https://github.com/stdlib-js/math/tree/main/iter/special/factorialln

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