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feat: add blas/ext/base/dwxmy #13688

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356 changes: 356 additions & 0 deletions lib/node_modules/@stdlib/blas/ext/base/dwxmy/README.md
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<!--

@license Apache-2.0

Copyright (c) 2026 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->

# dwxmy

> Perform the element-wise operation `w = x * y` for double-precision floating-point strided arrays.

@anandkaranubc anandkaranubc Jul 27, 2026

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Finally taking a step toward less verbose descriptions :)


<section class="intro">

This BLAS extension implements the operation

<!-- <equation class="equation" label="eq:wxmy" align="center" raw="\mathbf{w} = \mathbf{x} \odot \mathbf{y}" alt="Equation for wxmy operation."> -->

```math
\mathbf{w} = \mathbf{x} \odot \mathbf{y}
```

<!-- </equation> -->

where `⊙` denotes the [Hadamard product][hadamard-product].

</section>

<!-- /.intro -->

<section class="usage">

## Usage

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

#### dwxmy( N, x, strideX, y, strideY, w, strideW )

Performs the element-wise operation `w = x * y` for double-precision floating-point strided arrays.

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

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dwxmy( x.length, x, 1, y, 1, w, 1 );
// w => <Float64Array>[ 2.0, 6.0, 12.0, 20.0, 30.0 ]
```

The function has the following parameters:

- **N**: number of indexed elements.
- **x**: first input [`Float64Array`][@stdlib/array/float64].
- **strideX**: stride length for `x`.
- **y**: second input [`Float64Array`][@stdlib/array/float64].
- **strideY**: stride length for `y`.
- **w**: output [`Float64Array`][@stdlib/array/float64].
- **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`:

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

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dwxmy( 3, x, 2, y, 2, w, 2 );
// w => <Float64Array>[ 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`][mdn-typed-array] views.

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

// Initial arrays...
var x0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var w1 = new Float64Array( w0.buffer, w0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

dwxmy( 3, x1, 1, y1, 1, w1, 1 );
// w0 => <Float64Array>[ 0.0, 4.0, 9.0, 16.0, 0.0, 0.0 ]
```

<!-- lint disable maximum-heading-length -->

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

<!-- lint enable maximum-heading-length -->

Performs the element-wise operation `w = x * y` for double-precision floating-point strided arrays using alternative indexing semantics.

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

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var w = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dwxmy.ndarray( x.length, x, 1, 0, y, 1, 0, w, 1, 0 );
// w => <Float64Array>[ 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`][mdn-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`:

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

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var w = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dwxmy.ndarray( 3, x, 1, x.length-3, y, 1, y.length-3, w, 1, w.length-3 );
// w => <Float64Array>[ 0.0, 0.0, 9.0, 16.0, 25.0 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

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

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

var x = discreteUniform( 10, -100, 100, {
'dtype': 'float64'
});
console.log( x );

var y = discreteUniform( 10, -100, 100, {
'dtype': 'float64'
});
console.log( y );

var w = discreteUniform( 10, -100, 100, {
'dtype': 'float64'
});
console.log( w );

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

</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/dwxmy.h"
```

#### stdlib_strided_dwxmy( N, \*X, strideX, \*Y, strideY, \*W, strideW )

Performs the element-wise operation `W = X * Y` for double-precision floating-point strided arrays.

```c
const double x[] = { 1.0, 2.0, 3.0, 4.0 };
const double y[] = { 2.0, 3.0, 4.0, 5.0 };
double w[] = { 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dwxmy( 4, x, 1, y, 1, w, 1 );
```

The function accepts the following arguments:

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

```c
void stdlib_strided_dwxmy( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const double *Y, const CBLAS_INT strideY, double *W, const CBLAS_INT strideW );
```

<!-- lint disable maximum-heading-length -->

#### stdlib_strided_dwxmy_ndarray( N, \*X, strideX, offsetX, \*Y, strideY, offsetY, \*W, strideW, offsetW )

<!-- lint enable maximum-heading-length -->

Performs the element-wise operation `W = X * Y` for double-precision floating-point strided arrays using alternative indexing semantics.

```c
const double x[] = { 1.0, 2.0, 3.0, 4.0 };
const double y[] = { 2.0, 3.0, 4.0, 5.0 };
double w[] = { 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dwxmy_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] double*` first input array.
- **strideX**: `[in] CBLAS_INT` stride length for `X`.
- **offsetX**: `[in] CBLAS_INT` starting index for `X`.
- **Y**: `[in] double*` second input array.
- **strideY**: `[in] CBLAS_INT` stride length for `Y`.
- **offsetY**: `[in] CBLAS_INT` starting index for `Y`.
- **W**: `[out] double*` output array.
- **strideW**: `[in] CBLAS_INT` stride length for `W`.
- **offsetW**: `[in] CBLAS_INT` starting index for `W`.

```c
void stdlib_strided_dwxmy_ndarray( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, const double *Y, const CBLAS_INT strideY, const CBLAS_INT offsetY, double *W, const CBLAS_INT strideW, const CBLAS_INT offsetW );
```

</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/dwxmy.h"
#include <stdio.h>

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

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

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

// Perform the element-wise operation `w = x * y`:
stdlib_strided_dwxmy( N, x, strideX, y, strideY, w, strideW );

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

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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

<section class="related">

</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="links">

[@stdlib/array/float64]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float64

[hadamard-product]: https://en.wikipedia.org/wiki/Hadamard_product_(matrices)

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

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

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

</section>

<!-- /.links -->
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