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https://github.com/stdlib-js/random-iter-uniform

Create an iterator for generating pseudorandom numbers drawn from a continuous uniform distribution.
https://github.com/stdlib-js/random-iter-uniform

continuous generator iterator javascript math mathematics node node-js nodejs prng pseudorandom rand random rng seed seedable statistics stats stdlib uniform

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Create an iterator for generating pseudorandom numbers drawn from a continuous uniform distribution.

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README 

        



  

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# Uniform Random Numbers



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



> Create an iterator for generating pseudorandom numbers drawn from a [continuous uniform][uniform] distribution.



## Installation



```bash

npm install @stdlib/random-iter-uniform

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.



To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.



## Usage



```javascript

var iterator = require( '@stdlib/random-iter-uniform' );

```



#### iterator( a, b\[, options] )



Returns an iterator for generating pseudorandom numbers drawn from a [continuous uniform][uniform] distribution with parameters `a` (minimum support) and `b` (maximum support).



```javascript

var it = iterator( 2.0, 5.0 );

// returns 



var r = it.next().value;

// returns 



r = it.next().value;

// returns 



r = it.next().value;

// returns 



// ...

```



If the condition `a < b` is not satisfied, the function throws an error.



```javascript

var it = iterator( 13.0, 9.0 );

// throws 

```



The function accepts the following `options`:



-   **prng**: pseudorandom number generator for generating uniformly distributed pseudorandom numbers on the interval `[0,1)`. If provided, the function **ignores** both the `state` and `seed` options. In order to seed the returned iterator, one must seed the provided `prng` (assuming the provided `prng` is seedable).

-   **seed**: pseudorandom number generator seed.

-   **state**: a [`Uint32Array`][@stdlib/array/uint32] containing pseudorandom number generator state. If provided, the function ignores the `seed` option.

-   **copy**: `boolean` indicating whether to copy a provided pseudorandom number generator state. Setting this option to `false` allows sharing state between two or more pseudorandom number generators. Setting this option to `true` ensures that a returned iterator has exclusive control over its internal pseudorandom number generator state. Default: `true`.

-   **iter**: number of iterations.



To use a custom PRNG as the underlying source of uniformly distributed pseudorandom numbers, set the `prng` option.



```javascript

var minstd = require( '@stdlib/random-base-minstd' );



var it = iterator( 2.0, 4.0, {

    'prng': minstd.normalized

});



var r = it.next().value;

// returns 

```



To return an iterator having a specific initial state, set the iterator `state` option.



```javascript

var bool;

var it1;

var it2;

var r;

var i;



it1 = iterator( 2.0, 4.0 );



// Generate pseudorandom numbers, thus progressing the generator state:

for ( i = 0; i < 1000; i++ ) {

    r = it1.next().value;

}



// Create a new iterator initialized to the current state of `it1`:

it2 = iterator( 2.0, 4.0, {

    'state': it1.state

});



// Test that the generated pseudorandom numbers are the same:

bool = ( it1.next().value === it2.next().value );

// returns true

```



To seed the iterator, set the `seed` option.



```javascript

var it1 = iterator( 2.0, 4.0, {

    'seed': 12345

});



var r1 = it1.next().value;

// returns 



var it2 = iterator( 2.0, 4.0, {

    'seed': 12345

});



var r2 = it2.next().value;

// returns 



var bool = ( r1 === r2 );

// returns true

```



To limit the number of iterations, set the `iter` option.



```javascript

var it = iterator( 2.0, 4.0, {

    'iter': 2

});



var r = it.next().value;

// returns 



r = it.next().value;

// returns 



r = it.next().done;

// returns true

```



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



-   **next**: function which returns an iterator 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 and returns a single (optional) argument in an iterator protocol-compliant object.

-   **seed**: pseudorandom number generator seed. If provided a `prng` option, the property value is `null`.

-   **seedLength**: length of generator seed. If provided a `prng` option, the property value is `null`.

-   **state**: writable property for getting and setting the generator state. If provided a `prng` option, the property value is `null`.

-   **stateLength**: length of generator state. If provided a `prng` option, the property value is `null`.

-   **byteLength**: size (in bytes) of generator state. If provided a `prng` option, the property value is `null`.

-   **PRNG**: underlying pseudorandom number generator.



## Notes



-   If an environment supports `Symbol.iterator`, the returned iterator is iterable.

-   If PRNG state is "shared" (meaning a state array was provided during iterator creation and **not** copied) and one sets the underlying generator state to a state array having a different length, the iterator does **not** update the existing shared state and, instead, points to the newly provided state array. In order to synchronize the output of the underlying generator according to the new shared state array, the state array for **each** relevant iterator and/or PRNG must be **explicitly** set.

-   If PRNG state is "shared" and one sets the underlying generator state to a state array of the same length, the PRNG state is updated (along with the state of all other iterator and/or PRNGs sharing the PRNG's state array).



## Examples



```javascript

var iterator = require( '@stdlib/random-iter-uniform' );



var it;

var r;



// Create a seeded iterator for generating pseudorandom numbers:

it = iterator( 2.0, 5.0, {

    'seed': 1234,

    'iter': 10

});



// Perform manual iteration...

while ( true ) {

    r = it.next();

    if ( r.done ) {

        break;

    }

    console.log( r.value );

}

```



* * *



## See Also



-   [`@stdlib/random-base/uniform`][@stdlib/random/base/uniform]: uniformly distributed pseudorandom numbers.



* * *



## 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 © 2016-2024. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/random-iter-uniform.svg

[npm-url]: https://npmjs.org/package/@stdlib/random-iter-uniform



[test-image]: https://github.com/stdlib-js/random-iter-uniform/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/random-iter-uniform/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/random-iter-uniform/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/random-iter-uniform?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



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



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[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/random-iter-uniform/tree/deno

[deno-readme]: https://github.com/stdlib-js/random-iter-uniform/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/random-iter-uniform/tree/umd

[umd-readme]: https://github.com/stdlib-js/random-iter-uniform/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/random-iter-uniform/tree/esm

[esm-readme]: https://github.com/stdlib-js/random-iter-uniform/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/random-iter-uniform/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/random-iter-uniform/main/LICENSE



[uniform]: https://en.wikipedia.org/wiki/Uniform_distribution_%28continuous%29



[@stdlib/array/uint32]: https://github.com/stdlib-js/array-uint32



[@stdlib/random/base/uniform]: https://github.com/stdlib-js/random-base-uniform