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swxmy

Multiply elements of a single-precision floating-point strided array x by the corresponding elements of a single-precision floating-point strided array y and assign the results to elements in a single-precision floating-point strided array w.

This BLAS extension implements the operation

$$\mathbf{w} = \mathbf{x} \odot \mathbf{y}$$

where ⊙ denotes the Hadamard product.

Installation

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

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md 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

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

swxmy( N, x, strideX, y, strideY, w, strideW )

Multiplies elements of a single-precision floating-point strided array x by the corresponding elements of a single-precision floating-point strided array y and assigns the results to elements in a single-precision floating-point strided array w.

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

var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float32Array( [ 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

swxmy( x.length, x, 1, y, 1, w, 1 );
// w => <Float32Array>[ 2.0, 6.0, 12.0, 20.0, 30.0 ]

The function has the following parameters:

• N: number of indexed elements.
• x: first input Float32Array.
• strideX: stride length for x.
• y: second input Float32Array.
• strideY: stride length for y.
• w: output Float32Array.
• strideW: stride length for w.

The N and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to multiply every other element of x by every other element of y:

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

var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

swxmy( 3, x, 2, y, 2, w, 2 );
// w => <Float32Array>[ 1.0, 0.0, 9.0, 0.0, 25.0, 0.0 ]

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

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

// Initial arrays...
var x0 = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y0 = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w0 = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float32Array( y0.buffer, y0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var w1 = new Float32Array( w0.buffer, w0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

swxmy( 3, x1, 1, y1, 1, w1, 1 );
// w0 => <Float32Array>[ 0.0, 4.0, 9.0, 16.0, 0.0, 0.0 ]

swxmy.ndarray( N, x, strideX, offsetX, y, strideY, offsetY, w, strideW, offsetW )

Multiplies elements of a single-precision floating-point strided array x by the corresponding elements of a single-precision floating-point strided array y and assigns the results to elements in a single-precision floating-point strided array w using alternative indexing semantics.

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

var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float32Array( [ 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

swxmy.ndarray( x.length, x, 1, 0, y, 1, 0, w, 1, 0 );
// w => <Float32Array>[ 2.0, 6.0, 12.0, 20.0, 30.0 ]

The function has the following additional parameters:

• offsetX: starting index for x.
• offsetY: starting index for y.
• offsetW: starting index for w.

While 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 multiply the last three elements of x by the last three elements of y and assign to the last three elements of w:

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

var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var w = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

swxmy.ndarray( 3, x, 1, x.length-3, y, 1, y.length-3, w, 1, w.length-3 );
// w => <Float32Array>[ 0.0, 0.0, 9.0, 16.0, 25.0 ]

Notes

• If N <= 0, both functions return w unchanged.

Examples

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

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

var y = discreteUniform( 10, -100, 100, opts );
console.log( y );

var w = discreteUniform( 10, -100, 100, opts );
console.log( w );

swxmy( x.length, x, 1, y, 1, w, 1 );
console.log( w );

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C APIs

Usage

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

stdlib_strided_swxmy( N, *X, strideX, *Y, strideY, *W, strideW )

Multiplies elements of a single-precision floating-point strided array X by the corresponding elements of a single-precision floating-point strided array Y and assigns the results to elements in a single-precision floating-point strided array W.

const float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
const float y[] = { 2.0f, 3.0f, 4.0f, 5.0f };
float w[] = { 0.0f, 0.0f, 0.0f, 0.0f };

stdlib_strided_swxmy( 4, x, 1, y, 1, w, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] float* first input array.
• strideX: [in] CBLAS_INT stride length for X.
• Y: [in] float* second input array.
• strideY: [in] CBLAS_INT stride length for Y.
• W: [out] float* output array.
• strideW: [in] CBLAS_INT stride length for W.

void stdlib_strided_swxmy( const CBLAS_INT N, const float *X, const CBLAS_INT strideX, const float *Y, const CBLAS_INT strideY, float *W, const CBLAS_INT strideW );

stdlib_strided_swxmy_ndarray( N, *X, strideX, offsetX, *Y, strideY, offsetY, *W, strideW, offsetW )

Multiplies elements of a single-precision floating-point strided array X by the corresponding elements of a single-precision floating-point strided array Y and assigns the results to elements in a single-precision floating-point strided array W using alternative indexing semantics.

const float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
const float y[] = { 2.0f, 3.0f, 4.0f, 5.0f };
float w[] = { 0.0f, 0.0f, 0.0f, 0.0f };

stdlib_strided_swxmy_ndarray( 4, x, 1, 0, y, 1, 0, w, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] float* first input array.
• strideX: [in] CBLAS_INT stride length for X.
• offsetX: [in] CBLAS_INT starting index for X.
• Y: [in] float* second input array.
• strideY: [in] CBLAS_INT stride length for Y.
• offsetY: [in] CBLAS_INT starting index for Y.
• W: [out] float* output array.
• strideW: [in] CBLAS_INT stride length for W.
• offsetW: [in] CBLAS_INT starting index for W.

void stdlib_strided_swxmy_ndarray( const CBLAS_INT N, const float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, const float *Y, const CBLAS_INT strideY, const CBLAS_INT offsetY, float *W, const CBLAS_INT strideW, const CBLAS_INT offsetW );

Examples

#include "stdlib/blas/ext/base/swxmy.h"
#include <stdio.h>

int main( void ) {
    // Create strided arrays:
    const float x[] = { 1.0f, -2.0f, 3.0f, -4.0f, 5.0f, -6.0f, 7.0f, -8.0f };
    const float y[] = { 2.0f, 3.0f, -1.0f, 4.0f, -2.0f, 5.0f, -3.0f, 6.0f };
    float w[] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };

    // Specify the number of indexed elements:
    const int N = 8;

    // Specify strides:
    const int strideX = 1;
    const int strideY = 1;
    const int strideW = 1;

    // Multiply elements of `x` by the corresponding elements of `y` and assign the results to elements in `w`:
    stdlib_strided_swxmy( N, x, strideX, y, strideY, w, strideW );

    // Print the result:
    for ( int i = 0; i < 8; i++ ) {
        printf( "w[ %i ] = %f\n", i, w[ i ] );
    }
}

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Notice

This package is part of 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, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.