# @stdlib/blas-ext-base-sapxsumkbn2

> Add a scalar constant to each single-precision floating-point strided array element and compute the sum using a second-order iterative Kahan–Babuška algorithm.

Latest version **0.3.1** (published 2026-02-08) · Apache-2.0 license · 0 weekly downloads

## Install

```sh
npm install @stdlib/blas-ext-base-sapxsumkbn2
pnpm add @stdlib/blas-ext-base-sapxsumkbn2
yarn add @stdlib/blas-ext-base-sapxsumkbn2
bun add @stdlib/blas-ext-base-sapxsumkbn2
```

## Health

**Score 55/100 (C)** — status: stable.

Positive: has types; no vulnerabilities; high maintenance score.

Warnings: low downloads; no esm support; pre 1.0.

## Facts

| | |
|---|---|
| Version | 0.3.1 |
| Published | 2026-02-08 |
| First published | 2021-06-15 |
| Weekly downloads | 0 |
| License | Apache-2.0 |
| TypeScript types | bundled |
| Module format | CommonJS |
| Node | >=0.10.0 |
| Dependencies | 14 |
| Unpacked size | 55.8 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 1 |
| Author | The Stdlib Authors |
| Maintainers | stdlib-bot, kgryte, planeshifter, rreusser |
| Keywords | stdlib, stdmath, statistics, stats, mathematics, math, blas, extended, sum, total, summation, compensated, kahan, kbn, strided, strided array, typed, array, float32, float, single, float32array |

## Links

- npm: https://www.npmjs.com/package/@stdlib/blas-ext-base-sapxsumkbn2
- Repository: https://github.com/stdlib-js/blas-ext-base-sapxsumkbn2
- Homepage: https://stdlib.io
- Issues: https://github.com/stdlib-js/stdlib/issues
- Funding: https://opencollective.com/stdlib
- npm.io page: https://npm.io/package/@stdlib/blas-ext-base-sapxsumkbn2

## Dependencies (14)

- [@stdlib/napi-argv](https://npm.io/package/@stdlib/napi-argv.md) ^0.2.3
- [@stdlib/napi-export](https://npm.io/package/@stdlib/napi-export.md) ^0.3.1
- [@stdlib/assert-is-error](https://npm.io/package/@stdlib/assert-is-error.md) ^0.2.3
- [@stdlib/napi-argv-float](https://npm.io/package/@stdlib/napi-argv-float.md) ^0.2.3
- [@stdlib/napi-argv-int64](https://npm.io/package/@stdlib/napi-argv-int64.md) ^0.2.3
- [@stdlib/blas-base-shared](https://npm.io/package/@stdlib/blas-base-shared.md) ^0.2.1
- [@stdlib/utils-try-require](https://npm.io/package/@stdlib/utils-try-require.md) ^0.2.3
- [@stdlib/napi-create-double](https://npm.io/package/@stdlib/napi-create-double.md) ^0.0.3
- [@stdlib/blas-ext-base-ssumkbn2](https://npm.io/package/@stdlib/blas-ext-base-ssumkbn2.md) ^0.3.0
- [@stdlib/utils-library-manifest](https://npm.io/package/@stdlib/utils-library-manifest.md) ^0.2.4
- [@stdlib/strided-base-stride2offset](https://npm.io/package/@stdlib/strided-base-stride2offset.md) ^0.1.1
- [@stdlib/napi-argv-strided-float32array](https://npm.io/package/@stdlib/napi-argv-strided-float32array.md) ^0.2.3
- [@stdlib/number-float64-base-to-float32](https://npm.io/package/@stdlib/number-float64-base-to-float32.md) ^0.2.2
- [@stdlib/utils-define-nonenumerable-read-only-property](https://npm.io/package/@stdlib/utils-define-nonenumerable-read-only-property.md) ^0.2.3

## Recent versions

- 0.3.1 (latest) — 2026-02-08
- 0.3.0 — 2026-01-30
- 0.2.2 — 2024-07-28
- 0.2.1 — 2024-02-24
- 0.2.0 — 2024-02-14
- 0.1.0 — 2023-09-24
- 0.0.9 — 2022-08-29
- 0.0.8 — 2022-07-08
- 0.0.7 — 2022-07-07
- 0.0.6 — 2022-02-16
- 0.0.5 — 2021-08-22
- 0.0.4 — 2021-07-07
- 0.0.3 — 2021-06-28
- 0.0.2 — 2021-06-16
- 0.0.1 — 2021-06-15

## README

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<details>
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</details>

# sapxsumkbn2

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

> Add a scalar constant to each single-precision floating-point strided array element and compute the sum using a second-order iterative Kahan–Babuška algorithm.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/blas-ext-base-sapxsumkbn2
```

</section>

<section class="usage">

## Usage

```javascript
var sapxsumkbn2 = require( '@stdlib/blas-ext-base-sapxsumkbn2' );
```

#### sapxsumkbn2( N, alpha, x, strideX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );

var v = sapxsumkbn2( 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 [`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 access every other element:

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ] );

var v = sapxsumkbn2( 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.

<!-- eslint-disable stdlib/capitalized-comments -->

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var x0 = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = sapxsumkbn2( 4, 5.0, x1, 2 );
// returns 25.0
```

#### sapxsumkbn2.ndarray( N, alpha, x, strideX, offsetX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm and alternative indexing semantics.

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );

var v = sapxsumkbn2.ndarray( x.length, 5.0, x, 1, 0 );
// returns 16.0
```

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 every other element starting from the second element:

```javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );

var v = sapxsumkbn2.ndarray( 4, 5.0, x, 2, 1 );
// returns 25.0
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

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

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var sapxsumkbn2 = require( '@stdlib/blas-ext-base-sapxsumkbn2' );

var x = discreteUniform( 10, -100, 100, {
    'dtype': 'float32'
});
console.log( x );

var v = sapxsumkbn2( x.length, 5.0, x, 1 );
console.log( v );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/blas/ext/base/sapxsumkbn2.h"
```

#### stdlib_strided_sapxsumkbn2( N, alpha, \*X, strideX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.

```c
const float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };

float v = stdlib_strided_sapxsumkbn2( 4, 5.0f, x, 1 );
// returns 30.0f
```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.
-   **alpha**: `[in] float` scalar constant.
-   **X**: `[in] float*` input array.
-   **strideX**: `[in] CBLAS_INT` stride length.

```c
float stdlib_strided_sapxsumkbn2( const CBLAS_INT N, const float alpha, const float *X, const CBLAS_INT strideX );
```

#### stdlib_strided_sapxsumkbn2_ndarray( N, alpha, \*X, strideX, offsetX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm and alternative indexing semantics.

```c
const float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };

float v = stdlib_strided_sapxsumkbn2_ndarray( 4, 5.0f, x, 1, 0 );
// returns 30.0f
```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.
-   **alpha**: `[in] float` scalar constant.
-   **X**: `[in] float*` input array.
-   **strideX**: `[in] CBLAS_INT` stride length.
-   **offsetX**: `[in] CBLAS_INT` starting index.

```c
float stdlib_strided_sapxsumkbn2_ndarray( const CBLAS_INT N, const float alpha, const float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/blas/ext/base/sapxsumkbn2.h"
#include <stdio.h>

int main( void ) {
    // Create a strided array:
    const 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;

    // Compute the sum:
    float v = stdlib_strided_sapxsumkbn2( N, 5.0f, x, strideX );

    // Print the result:
    printf( "Sum: %f\n", v );
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<section class="references">

## References

-   Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." _Computing_ 76 (3): 279–93. doi:[10.1007/s00607-005-0139-x][@klein:2005a].

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/blas-ext/base/dapxsumkbn2`][@stdlib/blas/ext/base/dapxsumkbn2]</span><span class="delimiter">: </span><span class="description">add a scalar constant to each double-precision floating-point strided array element and compute the sum using a second-order iterative Kahan–Babuška algorithm.</span>
-   <span class="package-name">[`@stdlib/blas-ext/base/gapxsumkbn2`][@stdlib/blas/ext/base/gapxsumkbn2]</span><span class="delimiter">: </span><span class="description">add a scalar constant to each strided array element and compute the sum using a second-order iterative Kahan–Babuška algorithm.</span>
-   <span class="package-name">[`@stdlib/blas-ext/base/sapxsum`][@stdlib/blas/ext/base/sapxsum]</span><span class="delimiter">: </span><span class="description">add a constant to each single-precision floating-point strided array element and compute the sum.</span>
-   <span class="package-name">[`@stdlib/blas-ext/base/ssumkbn2`][@stdlib/blas/ext/base/ssumkbn2]</span><span class="delimiter">: </span><span class="description">calculate the sum of single-precision floating-point strided array elements using a second-order iterative Kahan–Babuška algorithm.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<section class="main-repo" >

* * *

## Notice

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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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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<!-- <related-links> -->

[@stdlib/blas/ext/base/dapxsumkbn2]: https://www.npmjs.com/package/@stdlib/blas-ext-base-dapxsumkbn2

[@stdlib/blas/ext/base/gapxsumkbn2]: https://www.npmjs.com/package/@stdlib/blas-ext-base-gapxsumkbn2

[@stdlib/blas/ext/base/sapxsum]: https://www.npmjs.com/package/@stdlib/blas-ext-base-sapxsum

[@stdlib/blas/ext/base/ssumkbn2]: https://www.npmjs.com/package/@stdlib/blas-ext-base-ssumkbn2

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