https://github.com/stdlib-js/blas-ext-base-sapx
Add a constant to each element in a single-precision floating-point strided array.
https://github.com/stdlib-js/blas-ext-base-sapx
add addition array blas extended float float32 float32array javascript math mathematics ndarray node node-js nodejs scale single stdlib strided translate
Last synced: 24 days ago
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Add a constant to each element in a single-precision floating-point strided array.
- Host: GitHub
- URL: https://github.com/stdlib-js/blas-ext-base-sapx
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-14T16:47:51.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2025-03-10T02:06:14.000Z (about 2 months ago)
- Last Synced: 2025-04-12T17:54:54.670Z (25 days ago)
- Topics: add, addition, array, blas, extended, float, float32, float32array, javascript, math, mathematics, ndarray, node, node-js, nodejs, scale, single, stdlib, strided, translate
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 554 KB
- Stars: 2
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
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README
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# sapx
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Add a scalar constant to each element in a single-precision floating-point strided array.
## Installation
```bash
npm install @stdlib/blas-ext-base-sapx
```
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 sapx = require( '@stdlib/blas-ext-base-sapx' );
```
#### sapx( N, alpha, x, strideX )
Adds a scalar constant to each element in a single-precision floating-point strided array.
```javascript
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
sapx( x.length, 5.0, x, 1 );
// x => [ 3.0, 6.0, 8.0, 0.0, 9.0, 5.0, 4.0, 2.0 ]
```
The function has the following parameters:
- **N**: number of indexed elements.
- **alpha**: scalar constant.
- **x**: input [`Float32Array`][@stdlib/array/float32].
- **strideX**: stride length.
The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to add a constant to every other element:
```javascript
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
sapx( 4, 5.0, x, 2 );
// x => [ 3.0, 1.0, 8.0, -5.0, 9.0, 0.0, 4.0, -3.0 ]
```
Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
```javascript
var Float32Array = require( '@stdlib/array-float32' );
// Initial array...
var x0 = new Float32Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );
// Create an offset view...
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
// Add a constant to every other element...
sapx( 3, 5.0, x1, 2 );
// x0 => [ 1.0, 3.0, 3.0, 1.0, 5.0, -1.0 ]
```
#### sapx.ndarray( N, alpha, x, strideX, offsetX )
Adds a scalar constant to each element in a single-precision floating-point strided array using alternative indexing semantics.
```javascript
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
sapx.ndarray( x.length, 5.0, x, 1, 0 );
// x => [ 3.0, 6.0, 8.0, 0.0, 9.0, 5.0, 4.0, 2.0 ]
```
The function has the following additional parameters:
- **offsetX**: starting index.
While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to access only the last three elements of the strided array:
```javascript
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );
sapx.ndarray( 3, 5.0, x, 1, x.length-3 );
// x => [ 1.0, -2.0, 3.0, 1.0, 10.0, -1.0 ]
```
## Notes
- If `N <= 0`, both functions return the input array unchanged.
## Examples
```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var sapx = require( '@stdlib/blas-ext-base-sapx' );
var x = discreteUniform( 10, -100, 100, {
'dtype': 'float32'
});
console.log( x );
sapx( x.length, 5.0, x, 1 );
console.log( x );
```
* * *
## C APIs
### Usage
```c
#include "stdlib/blas/ext/base/sapx.h"
```
#### stdlib_strided_sapx( N, alpha, \*X, strideX )
Adds a scalar constant to each element in a single-precision floating-point strided array.
```c
float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
stdlib_strided_sapx( 4, 5.0f, x, 1 );
```
The function accepts the following arguments:
- **N**: `[in] CBLAS_INT` number of indexed elements.
- **alpha**: `[in] float` scalar constant.
- **X**: `[inout] float*` input array.
- **strideX**: `[in] CBLAS_INT` stride length.
```c
void stdlib_strided_sapx( const CBLAS_INT N, const float alpha, float *X, const CBLAS_INT strideX );
```
#### stdlib_strided_sapx_ndarray( N, alpha, \*X, strideX, offsetX )
Adds a scalar constant to each element in a single-precision floating-point strided array using alternative indexing semantics.
```c
float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
stdlib_strided_sapx_ndarray( 4, 5.0f, x, 1, 0 );
```
The function accepts the following arguments:
- **N**: `[in] CBLAS_INT` number of indexed elements.
- **alpha**: `[in] float` scalar constant.
- **X**: `[inout] float*` input array.
- **strideX**: `[in] CBLAS_INT` stride length.
- **offsetX**: `[in] CBLAS_INT` starting index.
```c
void stdlib_strided_sapx_ndarray( const CBLAS_INT N, const float alpha, float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
```
### Examples
```c
#include "stdlib/blas/ext/base/sapx.h"
#include
int main( void ) {
// Create a strided array:
float x[] = { 1.0f, -2.0f, 3.0f, -4.0f, 5.0f, -6.0f, 7.0f, -8.0f };
// Specify the number of indexed elements:
const int N = 8;
// Specify a stride:
const int strideX = 1;
// Add a constant to each element:
stdlib_strided_sapx( N, 5.0f, x, strideX );
// Print the result:
for ( int i = 0; i < 8; i++ ) {
printf( "x[ %i ] = %f\n", i, x[ i ] );
}
}
```
* * *
## See Also
- [`@stdlib/blas-ext/base/dapx`][@stdlib/blas/ext/base/dapx]: add a scalar constant to each element in a double-precision floating-point strided array.
- [`@stdlib/blas-ext/base/gapx`][@stdlib/blas/ext/base/gapx]: add a scalar constant to each element in a strided array.
* * *
## 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 © 2016-2025. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/blas-ext-base-sapx.svg
[npm-url]: https://npmjs.org/package/@stdlib/blas-ext-base-sapx
[test-image]: https://github.com/stdlib-js/blas-ext-base-sapx/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/blas-ext-base-sapx/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/blas-ext-base-sapx/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/blas-ext-base-sapx?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/blas-ext-base-sapx/tree/deno
[deno-readme]: https://github.com/stdlib-js/blas-ext-base-sapx/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/blas-ext-base-sapx/tree/umd
[umd-readme]: https://github.com/stdlib-js/blas-ext-base-sapx/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/blas-ext-base-sapx/tree/esm
[esm-readme]: https://github.com/stdlib-js/blas-ext-base-sapx/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/blas-ext-base-sapx/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/blas-ext-base-sapx/main/LICENSE
[@stdlib/array/float32]: https://github.com/stdlib-js/array-float32
[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
[@stdlib/blas/ext/base/dapx]: https://github.com/stdlib-js/blas-ext-base-dapx
[@stdlib/blas/ext/base/gapx]: https://github.com/stdlib-js/blas-ext-base-gapx