Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/stdlib-js/math-strided-ops-sub

Element-wise subtraction of two strided arrays.
https://github.com/stdlib-js/math-strided-ops-sub

add addition arithmetic array element-wise javascript math mathematics minus ndarray node node-js nodejs stdlib strided subtract subtraction sum summation vector

Last synced: 2 days ago
JSON representation

Element-wise subtraction of two strided arrays.

Awesome Lists containing this project

README 

        



  

    About stdlib...

  

  
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.


  
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.


  
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.


  
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!



# sub



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



> Element-wise subtraction of two strided arrays.



## Installation



```bash

npm install @stdlib/math-strided-ops-sub

```



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 sub = require( '@stdlib/math-strided-ops-sub' );

```



#### sub( N, dtypeX, x, strideX, dtypeY, y, strideY, dtypeZ, z, strideZ )



Subtracts each element in a strided array `x` to a corresponding element in a strided array `y` and assigns the results to elements in a strided array `z`.



```javascript

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



var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0 ] );

var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );

var z = new Float64Array( x.length );



sub( x.length, 'float64', x, 1, 'float64', y, 1, 'float64', z, 1 );

// z => [ -3.0, -1.0, 0.0, -9.0, -1.0 ]

```



The function accepts the following arguments:



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

-   **dtypeX**: [data type][@stdlib/strided/dtypes] for `x`.

-   **x**: input array-like object.

-   **strideX**: index increment for `x`.

-   **dtypeY**: [data type][@stdlib/strided/dtypes] for `y`.

-   **y**: input array-like object.

-   **strideY**: index increment for `y`.

-   **dtypeZ**: [data type][@stdlib/strided/dtypes] for `z`.

-   **z**: output array-like object.

-   **strideZ**: index increment for `z`.



The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to index every other value in `x` and the first `N` elements of `y` in reverse order,



```javascript

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



var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0 ] );

var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

var z = new Float64Array( x.length );



sub( 3, 'float64', x, 2, 'float64', y, -1, 'float64', z, 1 );

// z => [ -5.0, 1.0, 3.0, 0.0, 0.0, 0.0 ]

```



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 arrays...

var x0 = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0 ] );

var y0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

var z0 = new Float64Array( x0.length );



// Create offset views...

var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element

var z1 = new Float64Array( z0.buffer, z0.BYTES_PER_ELEMENT*2 ); // start at 3rd element



sub( 3, 'float64', x1, -2, 'float64', y1, 1, 'float64', z1, 1 );

// z0 => [ 0.0, 0.0, -4.0, 0.0, -5.0, 0.0 ]

```



#### sub.ndarray( N, dtypeX, x, strideX, offsetX, dtypeY, y, strideY, offsetY, dtypeZ, z, strideZ, offsetZ )



Subtracts each element in a strided array `x` to a corresponding element in a strided array `y` and assigns the results to elements in a strided array `z` using alternative indexing semantics.



```javascript

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



var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0 ] );

var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );

var z = new Float64Array( x.length );



sub.ndarray( x.length, 'float64', x, 1, 0, 'float64', y, 1, 0, 'float64', z, 1, 0 );

// z => [ -3.0, -1.0, 0.0, -9.0, -1.0 ]

```



The function accepts the following additional arguments:



-   **offsetX**: starting index for `x`.

-   **offsetY**: starting index for `y`.

-   **offsetZ**: starting index for `z`.



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 index every other value in `x` starting from the second value and to index the last `N` elements in `y` in reverse order,



```javascript

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



var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0 ] );

var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

var z = new Float64Array( x.length );



sub.ndarray( 3, 'float64', x, 2, 1, 'float64', y, -1, y.length-1, 'float64', z, 1, 0 );

// z => [ -5.0, 0.0, -4.0, 0.0, 0.0, 0.0 ]

```



## Examples



```javascript

var uniform = require( '@stdlib/random-base-discrete-uniform' ).factory;

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

var filledarrayBy = require( '@stdlib/array-filled-by' );

var sub = require( '@stdlib/math-strided-ops-sub' );



var dt;

var x;

var y;

var z;

var i;



dt = [ 'float64', 'float32', 'int32', 'uint8', 'generic' ];



for ( i = 0; i < dt.length; i++ ) {

    x = filledarrayBy( 10, dt[ i ], uniform( 0.0, 10.0 ) );

    console.log( x );



    y = filledarrayBy( x.length, dt[ i ], uniform( 0.0, 10.0 ) );

    console.log( y );



    z = filledarray( 0.0, x.length, 'generic' );

    console.log( z );



    sub.ndarray( x.length, dt[ i ], x, 1, 0, dt[ i ], y, 1, 0, 'generic', z, -1, z.length-1 );

    console.log( z );

    console.log( '' );

}

```



* * *



## See Also



-   [`@stdlib/math-strided/ops/add`][@stdlib/math/strided/ops/add]: element-wise addition of two strided arrays.

-   [`@stdlib/math-strided/ops/mul`][@stdlib/math/strided/ops/mul]: element-wise multiplication of two strided arrays.



* * *



## 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/math-strided-ops-sub.svg

[npm-url]: https://npmjs.org/package/@stdlib/math-strided-ops-sub



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

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



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

[coverage-url]: https://codecov.io/github/stdlib-js/math-strided-ops-sub?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/math-strided-ops-sub/tree/deno

[deno-readme]: https://github.com/stdlib-js/math-strided-ops-sub/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/math-strided-ops-sub/tree/umd

[umd-readme]: https://github.com/stdlib-js/math-strided-ops-sub/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/math-strided-ops-sub/tree/esm

[esm-readme]: https://github.com/stdlib-js/math-strided-ops-sub/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/math-strided-ops-sub/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-strided-ops-sub/main/LICENSE



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



[@stdlib/strided/dtypes]: https://github.com/stdlib-js/strided-dtypes



[@stdlib/math/strided/ops/add]: https://github.com/stdlib-js/math-strided-ops-add



[@stdlib/math/strided/ops/mul]: https://github.com/stdlib-js/math-strided-ops-mul