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sapxsum

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

Usage

import sapxsum from 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-ext-base-sapxsum@deno/mod.js';

sapxsum( N, alpha, x, strideX )

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

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';

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

var v = sapxsum( 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.
• 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:

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';

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

var v = sapxsum( 4, 5.0, x, 2 );
// returns 25.0

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';

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 = sapxsum( 4, 5.0, x1, 2 );
// returns 25.0

sapxsum.ndarray( N, alpha, x, strideX, offsetX )

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

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';

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

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

The function has the following additional parameters:

• offsetX: starting index.

While 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:

import Float32Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float32@deno/mod.js';

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

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

Notes

• If N <= 0, both functions return 0.0.

Examples

import discreteUniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@deno/mod.js';
import sapxsum from 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-ext-base-sapxsum@deno/mod.js';

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

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

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See Also

• @stdlib/blas-ext/base/dapxsum: add a scalar constant to each double-precision floating-point strided array element and compute the sum.
• @stdlib/blas-ext/base/gapxsum: add a scalar constant to each strided array element and compute the sum.
• @stdlib/blas-ext/base/sapxsumpw: add a scalar constant to each single-precision floating-point strided array element and compute the sum using pairwise summation.
• @stdlib/blas-ext/base/ssum: calculate the sum of single-precision floating-point strided array elements.

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Notice

This package is part of stdlib, a standard library 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, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.