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https://github.com/stdlib-js/blas-ext-base-dapxsum

Adds a constant to each double-precision floating-point strided array element and computes the sum.
https://github.com/stdlib-js/blas-ext-base-dapxsum

array blas double extended float64 javascript math mathematics node node-js nodejs statistics stats stdlib strided strided-array sum summation total typed

Last synced: 10 days ago
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Adds a constant to each double-precision floating-point strided array element and computes the sum.

Host: GitHub
URL: https://github.com/stdlib-js/blas-ext-base-dapxsum
Owner: stdlib-js
License: apache-2.0
Created: 2021-06-15T16:53:54.000Z (over 3 years ago)
Default Branch: main
Last Pushed: 2025-01-22T03:51:27.000Z (12 days ago)
Last Synced: 2025-01-22T04:26:54.752Z (12 days ago)
Topics: array, blas, double, extended, float64, javascript, math, mathematics, node, node-js, nodejs, statistics, stats, stdlib, strided, strided-array, sum, summation, total, typed
Language: JavaScript
Homepage: https://github.com/stdlib-js/stdlib
Size: 947 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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  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!


# dapxsum

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

> Add a scalar constant to each double-precision floating-point strided array element and compute the sum.

## Installation

```bash

npm install @stdlib/blas-ext-base-dapxsum

```

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 dapxsum = require( '@stdlib/blas-ext-base-dapxsum' );

```

#### dapxsum( N, alpha, x, strideX )

Adds a scalar constant to each double-precision floating-point strided array element and computes the sum.

```javascript

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

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

var v = dapxsum( x.length, 5.0, x, 1 );

// returns 16.0

```

The function has the following parameters:

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

-   **alpha**: scalar constant.

-   **x**: input [`Float64Array`][@stdlib/array/float64].

-   **strideX**: stride length for `x`.

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

```javascript

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

var x = new Float64Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ] );

var v = dapxsum( 4, 5.0, x, 2 );

// returns 25.0

```

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' );

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

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

var v = dapxsum( 4, 5.0, x1, 2 );

// returns 25.0

```

#### dapxsum.ndarray( N, alpha, x, strideX, offsetX )

Adds a scalar constant to each double-precision floating-point strided array element and computes the sum using alternative indexing semantics.

```javascript

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

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

var v = dapxsum.ndarray( x.length, 5.0, x, 1, 0 );

// returns 16.0

```

The function has the following additional parameters:

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

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 every element starting from the second element:

```javascript

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

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

var v = dapxsum.ndarray( 4, 5.0, x, 2, 1 );

// returns 25.0

```

## Notes

-   If `N <= 0`, both functions return `0.0`.

## Examples

```javascript

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );

var dapxsum = require( '@stdlib/blas-ext-base-dapxsum' );

var x = discreteUniform( 10, -100, 100, {

    'dtype': 'float64'

});

console.log( x );

var v = dapxsum( x.length, 5.0, x, 1 );

console.log( v );

```

* * *

## C APIs

### Usage

```c

#include "stdlib/blas/ext/base/dapxsum.h"

```

#### stdlib_strided_dapxsum( N, alpha, \*X, strideX )

Adds a scalar constant to each double-precision floating-point strided array element and computes the sum.

```c

const double x[] = { 1.0, 2.0, 3.0, 4.0 };

double v = stdlib_strided_dapxsum( 4, 5.0, x, 1 );

// returns 30.0

```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.

-   **alpha**: `[in] double` scalar constant.

-   **X**: `[in] double*` input array.

-   **strideX**: `[in] CBLAS_INT` stride length for `X`.

```c

double stdlib_strided_dapxsum( const CBLAS_INT N, const double alpha, const double *X, const CBLAS_INT strideX );

```

#### stdlib_strided_dapxsum_ndarray( N, alpha, \*X, strideX, offsetX )

Adds a scalar constant to each double-precision floating-point strided array element and computes the sum using alternative indexing semantics.

```c

double x[] = { 1.0, 2.0, 3.0, 4.0 };

double v = stdlib_strided_dapxsum_ndarray( 4, 5.0, x, 1, 0 );

// returns 30.0

```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.

-   **alpha**: `[in] double` scalar constant.

-   **X**: `[in] double*` input array.

-   **strideX**: `[in] CBLAS_INT` stride length for `X`.

-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.

```c

double stdlib_strided_dapxsum_ndarray( const CBLAS_INT N, const double alpha, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );

```

### Examples

```c

#include "stdlib/blas/ext/base/dapxsum.h"

#include 

int main( void ) {

    // Create a strided array:

    const double x[] = { 1.0, -2.0, 3.0, -4.0, 5.0, -6.0, 7.0, -8.0 };

    // Specify the number of indexed elements:

    const int N = 8;

    // Specify a stride:

    const int strideX = 1;

    // Compute the sum:

    double v = stdlib_strided_dapxsum( N, 5.0, x, strideX );

    // Print the result:

    printf( "Sum: %lf\n", sum );

}

```

* * *

## See Also

-   [`@stdlib/blas-ext/base/dapxsumpw`][@stdlib/blas/ext/base/dapxsumpw]: add a scalar constant to each double-precision floating-point strided array element and compute the sum using pairwise summation.

-   [`@stdlib/blas-ext/base/dsum`][@stdlib/blas/ext/base/dsum]: calculate the sum of double-precision floating-point strided array elements.

-   [`@stdlib/blas-ext/base/gapxsum`][@stdlib/blas/ext/base/gapxsum]: add a scalar constant to each strided array element and compute the sum.

-   [`@stdlib/blas-ext/base/sapxsum`][@stdlib/blas/ext/base/sapxsum]: add a constant to each single-precision floating-point strided array element and compute the sum.

* * *

## 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-dapxsum.svg

[npm-url]: https://npmjs.org/package/@stdlib/blas-ext-base-dapxsum

[test-image]: https://github.com/stdlib-js/blas-ext-base-dapxsum/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/blas-ext-base-dapxsum/actions/workflows/test.yml?query=branch:main

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/blas-ext-base-dapxsum/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/blas-ext-base-dapxsum?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-dapxsum/tree/deno

[deno-readme]: https://github.com/stdlib-js/blas-ext-base-dapxsum/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/blas-ext-base-dapxsum/tree/umd

[umd-readme]: https://github.com/stdlib-js/blas-ext-base-dapxsum/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/blas-ext-base-dapxsum/tree/esm

[esm-readme]: https://github.com/stdlib-js/blas-ext-base-dapxsum/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/blas-ext-base-dapxsum/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/blas-ext-base-dapxsum/main/LICENSE

[@stdlib/array/float64]: https://github.com/stdlib-js/array-float64

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

[@stdlib/blas/ext/base/dapxsumpw]: https://github.com/stdlib-js/blas-ext-base-dapxsumpw

[@stdlib/blas/ext/base/dsum]: https://github.com/stdlib-js/blas-ext-base-dsum

[@stdlib/blas/ext/base/gapxsum]: https://github.com/stdlib-js/blas-ext-base-gapxsum

[@stdlib/blas/ext/base/sapxsum]: https://github.com/stdlib-js/blas-ext-base-sapxsum