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https://github.com/stdlib-js/random-strided-t

Fill a strided array with pseudorandom numbers drawn from a Student's t distribution.
https://github.com/stdlib-js/random-strided-t

continuous gaussian generator javascript math mathematics node node-js nodejs normal prng pseudorandom rand random rng statistics stats stdlib student t

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Fill a strided array with pseudorandom numbers drawn from a Student's t distribution.

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README 

        



  

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# Student's t Random Numbers



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



> Fill a strided array with pseudorandom numbers drawn from a [Student's t][@stdlib/random/base/t]-distribution.



## Installation



```bash

npm install @stdlib/random-strided-t

```



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 t = require( '@stdlib/random-strided-t' );

```



#### t( N, v, sv, out, so )



Fills a strided array with pseudorandom numbers drawn from a [Student's t][@stdlib/random/base/t]-distribution.



```javascript

var Float64Array = require( '@stdlib/array-float64' );



// Create an array:

var out = new Float64Array( 10 );



// Fill the array with pseudorandom numbers:

t( out.length, [ 2.0 ], 0, out, 1 );

```



The function has the following parameters:



-   **N**: number of indexed elements.

-   **v**: rate parameter.

-   **sv**: index increment for `v`.

-   **out**: output array.

-   **so**: index increment for `out`.



The `N` and stride parameters determine which strided array elements are accessed at runtime. For example, to access every other value in `out`,



```javascript

var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];



t( 3, [ 2.0 ], 0, out, 2 );

```



Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.



```javascript

var Float64Array = require( '@stdlib/array-float64' );



// Initial array:

var v0 = new Float64Array( [ 2.0, 2.0, 2.0, 2.0, 2.0, 2.0 ] );



// Create offset view:

var v1 = new Float64Array( v0.buffer, v0.BYTES_PER_ELEMENT*3 ); // start at 4th element



// Create an output array:

var out = new Float64Array( 3 );



// Fill the output array:

t( out.length, v1, -1, out, 1 );

```



#### t.ndarray( N, v, sv, ov, out, so, oo )



Fills a strided array with pseudorandom numbers drawn from a [Student's t][@stdlib/random/base/t]-distribution using alternative indexing semantics.



```javascript

var Float64Array = require( '@stdlib/array-float64' );



// Create an array:

var out = new Float64Array( 10 );



// Fill the array with pseudorandom numbers:

t.ndarray( out.length, [ 2.0 ], 0, 0, out, 1, 0 );

```



The function has the following additional parameters:



-   **ov**: starting index for `v`.

-   **oo**: starting index for `out`.



While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the offset parameters support indexing semantics based on starting indices. For example, to access every other value in `out` starting from the second value,



```javascript

var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];



t.ndarray( 3, [ 2.0 ], 0, 0, out, 2, 1 );

```



#### t.factory( \[options] )



Returns a function for filling strided arrays with pseudorandom numbers drawn from a [Student's t][@stdlib/random/base/t]-distribution.



```javascript

var Float64Array = require( '@stdlib/array-float64' );



var random = t.factory();

// returns 



// Create an array:

var out = new Float64Array( 10 );



// Fill the array with pseudorandom numbers:

random( out.length, [ 2.0 ], 0, out, 1 );

```



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 underlying pseudorandom number generator, 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 an underlying generator has exclusive control over its internal state. Default: `true`.



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



```javascript

var Float64Array = require( '@stdlib/array-float64' );

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



var opts = {

    'prng': minstd.normalized

};

var random = t.factory( opts );



var out = new Float64Array( 10 );

random( out.length, [ 2.0 ], 0, out, 1 );

```



To seed the underlying pseudorandom number generator, set the `seed` option.



```javascript

var Float64Array = require( '@stdlib/array-float64' );



var opts = {

    'seed': 12345

};

var random = t.factory( opts );



var out = new Float64Array( 10 );

random( out.length, [ 2.0 ], 0, out, 1 );

```



* * *



#### random.PRNG



The underlying pseudorandom number generator.



```javascript

var prng = t.PRNG;

// returns 

```



#### t.seed



The value used to seed the underlying pseudorandom number generator.



```javascript

var seed = t.seed;

// returns 

```



If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.



```javascript

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



var random = t.factory({

    'prng': minstd

});

// returns 



var seed = random.seed;

// returns null

```



#### t.seedLength



Length of underlying pseudorandom number generator seed.



```javascript

var len = t.seedLength;

// returns 

```



If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.



```javascript

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



var random = t.factory({

    'prng': minstd

});

// returns 



var len = random.seedLength;

// returns null

```



#### t.state



Writable property for getting and setting the underlying pseudorandom number generator state.



```javascript

var state = t.state;

// returns 

```



If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.



```javascript

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



var random = t.factory({

    'prng': minstd

});

// returns 



var state = random.state;

// returns null

```



#### t.stateLength



Length of underlying pseudorandom number generator state.



```javascript

var len = t.stateLength;

// returns 

```



If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.



```javascript

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



var random = t.factory({

    'prng': minstd

});

// returns 



var len = random.stateLength;

// returns null

```



#### t.byteLength



Size (in bytes) of underlying pseudorandom number generator state.



```javascript

var sz = t.byteLength;

// returns 

```



If the `factory` method is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.



```javascript

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



var random = t.factory({

    'prng': minstd

});

// returns 



var sz = random.byteLength;

// returns null

```



* * *



## Notes



-   If `N <= 0`, both `t` and `t.ndarray` leave the output array unchanged.

-   Both `t` and `t.ndarray` support array-like objects having getter and setter accessors for array element access.



* * *



## Examples



```javascript

var zeros = require( '@stdlib/array-zeros' );

var zeroTo = require( '@stdlib/array-zero-to' );

var logEach = require( '@stdlib/console-log-each' );

var t = require( '@stdlib/random-strided-t' );



// Specify a PRNG seed:

var opts = {

    'seed': 1234

};



// Create a seeded PRNG:

var rand1 = t.factory( opts );



// Create an array:

var x1 = zeros( 10, 'float64' );



// Fill the array with pseudorandom numbers:

rand1( x1.length, [ 2.0 ], 0, x1, 1 );



// Create another function for filling strided arrays:

var rand2 = t.factory( opts );

// returns 



// Create a second array:

var x2 = zeros( 10, 'generic' );



// Fill the array with the same pseudorandom numbers:

rand2( x2.length, [ 2.0 ], 0, x2, 1 );



// Create a list of indices:

var idx = zeroTo( x1.length, 'generic' );



// Print the array contents:

logEach( 'x1[%d] = %.2f; x2[%d] = %.2f', idx, x1, idx, x2 );

```



* * *



## See Also



-   [`@stdlib/random-base/t`][@stdlib/random/base/t]: Student's t-distributed pseudorandom numbers.

-   [`@stdlib/random-array/t`][@stdlib/random/array/t]: create an array containing pseudorandom numbers drawn from a Student's t-distribution.



* * *



## 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-strided-t.svg

[npm-url]: https://npmjs.org/package/@stdlib/random-strided-t



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

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



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

[coverage-url]: https://codecov.io/github/stdlib-js/random-strided-t?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-strided-t/tree/deno

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

[umd-url]: https://github.com/stdlib-js/random-strided-t/tree/umd

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

[esm-url]: https://github.com/stdlib-js/random-strided-t/tree/esm

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

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



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



[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray



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



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



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