Skip to content

feat: add blas/ext/base/ddiff #10376

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
headlessNode wants to merge 5 commits into
base: develop
Choose a base branch
from
+5,045 −0
Open

feat: add blas/ext/base/ddiff #10376

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
8f38374
feat: add blas/ext/base/ddiff
headlessNode Feb 19, 2026
c24bbdb
docs: apply suggestions from code review
headlessNode Feb 19, 2026
a7c2675
docs: apply suggestions from code review
headlessNode Feb 19, 2026
d4b2ee6
docs: apply suggestions from code review
headlessNode Feb 19, 2026
bac8821
docs: apply suggestion from code review
headlessNode Feb 19, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
391 changes: 391 additions & 0 deletions lib/node_modules/@stdlib/blas/ext/base/ddiff/README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,391 @@
<!--

@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.

-->

# ddiff

> Calculate the k-th discrete forward difference of a double-precision floating-point strided array.

<section class="usage">

## Usage

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

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

#### ddiff( N, k, x, strideX, N1, prepend, strideP, N2, append, strideA, out, strideOut, workspace, strideW )

Calculates the k-th discrete forward differences of a double-precision floating-point strided array.

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

var x = new Float64Array( [ 2.0, 4.0, 6.0, 8.0, 10.0 ] );
var p = new Float64Array( [ 1.0 ] );
var a = new Float64Array( [ 11.0 ] );
var out = new Float64Array( 6 );
var w = new Float64Array( 6 );

ddiff( x.length, 1, x, 1, 1, p, 1, 1, a, 1, out, 1, w, 1 );

console.log( out );
// out => <Float64Array>[ 1.0, 2.0, 2.0, 2.0, 2.0, 1.0 ]
```

The function has the following parameters:

- **N**: number of indexed elements.
- **k**: number of times to recursively compute differences.
- **x**: input [`Float64Array`][@stdlib/array/float64].
- **strideX**: stride length for `x`.
- **N1**: number of elements to `prepend`.
- **prepend**: a [`Float64Array`][@stdlib/array/float64] containing values to prepend prior to computing differences.
- **strideP**: stride length for `prepend`.
- **N2**: number of elements to `append`.
- **append**: a [`Float64Array`][@stdlib/array/float64] containing values to append prior to computing differences..
- **strideA**: strides length for `append`.
- **out**: output [`Float64Array`][@stdlib/array/float64].
- **strideOut**: stride length for `out`.
- **workspace**: workspace [`Float64Array`][@stdlib/array/float64].
- **strideW**: stride length for `workspace`.

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

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

var x = new Float64Array( [ 2.0, 4.0, 6.0, 8.0, 10.0 ] );
var p = new Float64Array( [ 1.0 ] )
var a = new Float64Array( [ 11.0 ] );
var out = new Float64Array( 4 );
var w = new Float64Array( 4 );

ddiff( 3, 1, x, 2, 1, p, 1, 1, a, 1, out, 1, w, 1 );

console.log( out );
// out => <Float64Array>[ 1.0, 4.0, 4.0, 1.0 ]
```

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 array...
var x0 = new Float64Array( [ 2.0, 4.0, 6.0, 8.0, 10.0 ] );

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

var p = new Float64Array( [ 1.0 ] )
var a = new Float64Array( [ 11.0 ] );
var out = new Float64Array( 5 );
var w = new Float64Array( 5 );

ddiff( x1.length, 1, x1, 1, 1, p, 1, 1, a, 1, out, 1, w, 1 );

console.log( out );
// out => <Float64Array>[ 3.0, 2.0, 2.0, 2.0, 11.0 ]
```

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

#### ddiff.ndarray( N, k, x, strideX, offsetX, N1, prepend, strideP, offsetP, N2, append, strideA, offsetA, out, strideOut, offsetOut, workspace, strideW, offsetW )

Calculates the k-th discrete forward differences of a double-precision floating-point strided array using alternative indexing semantics.

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

var x = new Float64Array( [ 2.0, 4.0, 6.0, 8.0, 10.0 ] );
var p = new Float64Array( [ 1.0 ] );
var a = new Float64Array( [ 11.0 ] );
var out = new Float64Array( 6 );
var w = new Float64Array( 6 );

ddiff( x.length, 1, x, 1, 0, 1, p, 1, 0, 1, a, 1, 0, out, 1, 0, w, 1, 0 );

console.log( out );
// out => <Float64Array>[ 1.0, 2.0, 2.0, 2.0, 2.0, 1.0 ]
```

The function has the following additional parameters:

- **offsetX**: starting index for `x`.
- **offsetP**: starting index for `prepend`.
- **offsetA**: starting index for `append`.
- **offsetOut**: starting index for `out`.
- **offsetW**: starting index of `workspace`.

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 only the last three elements:

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

var x = new Float64Array( [ 2.0, 4.0, 6.0, 8.0, 10.0 ] );
var p = new Float64Array( [ 1.0 ] )
var a = new Float64Array( [ 11.0 ] );
var out = new Float64Array( 4 );
var w = new Float64Array( 4 );

ddiff( 3, 1, x, 1, x.length-3, 1, p, 1, 0, 1, a, 1, 0, out, 1, 0, w, 1, 0 );

console.log( out );
// out => <Float64Array>[ 5.0, 2.0, 2.0, 1.0 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

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

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var Float64Array = require( '@stdlib/array/float64' );
var ddiff = require( '@stdlib/blas/ext/base/ddiff' );

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

var p = discreteUniform( 2, -100, 100, {
'dtype': 'float64'
});
console.log( 'Prepend array: ', p );

var a = discreteUniform( 2, -100, 100, {
'dtype': 'float64'
});
console.log( 'Append array: ', a );

var out = new Float64Array( 10 );

var w = new Float64Array( 13 );

ddiff( x.length, 4, x, 1, 2, p, 1, 2, a, 1, out, 1, w, 1 );
console.log( 'Output', out );
```

</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/ddiff.h"
```

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

#### stdlib_strided_ddiff( N, k, x, strideX, N1, prepend, strideP, N2, append, strideA, \*out, strideOut, workspace, strideW )

Calculates the k-th discrete forward differences of a double-precision floating-point strided array.

```c
double x[] = { 2.0, 4.0, 6.0, 8.0, 10.0 };
double p[] = { 1.0 };
double a[] = { 11.0 };
double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
double w[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_ddiff( 5, 1, x, 1, 1, p, 1, 1, a, 1, out, 1, w, 1 );
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **k**: `[in] CBLAS_INT` number of times to recursively compute differences.
- **x**: `[in] double` input [`Float64Array`][@stdlib/array/float64].
- **strideX**: `[in] CBLAS_INT` stride length for `x`.
- **N1**: `[in] CBLAS_INT` number of elements in `prepend`.
- **prepend**: `[in] double` a [`Float64Array`][@stdlib/array/float64] containing values to prepend prior to computing differences.
- **strideP**: `[in] CBLAS_INT` stride length for `prepend`.
- **N2**: `[in] CBLAS_INT` number of elements in `append`.
- **append**: `[in] double` a [`Float64Array`][@stdlib/array/float64] containing values to append prior to computing differences..
- **strideA**: `[in] CBLAS_INT` strides length for `append`.
- **out**: `[in] double` output [`Float64Array`][@stdlib/array/float64].
- **strideOut**: `[in] CBLAS_INT` stride length for `out`.
- **workspace**: `[in] double` workspace [`Float64Array`][@stdlib/array/float64].
- **strideW**: `[in] CBLAS_INT` stride length for `workspace`.

```c
void stdlib_strided_ddiff( const CBLAS_INT N, const CBLAS_INT k, double *X, const CBLAS_INT strideX, const CBLAS_INT N1, double *prepend, const CBLAS_INT strideP, const CBLAS_INT N2, double *append, const CBLAS_INT strideA, double *out, const CBLAS_INT strideOut, const double workspace, const CBLAS_INT strideW );
```

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

#### stdlib_strided_ddiff_ndarray( N, k, x, strideX, offsetX, N1, prepend, strideP, offsetP, N2, append, strideA, offsetA, \*out, strideOut, offsetOut, w, strideW, offsetW )

Calculates the k-th discrete forward differences of a double-precision floating-point strided array using alternative indexing semantics.

```c
double x[] = { 2.0, 4.0, 6.0, 8.0, 10.0 };
double p[] = { 1.0 };
double a[] = { 11.0 };
double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
double w[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_ddiff_ndarray( 5, 1, x, 1, 0, 1, p, 1, 0, 1, a, 1, 0, out, 1, 0, w, 1, 0 );
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **k**: `[in] CBLAS_INT` number of times to recursively compute differences.
- **x**: `[in] double` input [`Float64Array`][@stdlib/array/float64].
- **strideX**: `[in] CBLAS_INT` stride length for `x`.
- **offsetX**: `[in] CBLAS_INT` starting index for `x`.
- **N1**: `[in] CBLAS_INT` number of elements in `prepend`.
- **prepend**: `[in] double` a [`Float64Array`][@stdlib/array/float64] containing values to prepend prior to computing differences.
- **strideP**: `[in] CBLAS_INT` stride length for `prepend`.
- **offsetP**: `[in] CBLAS_INT` starting index for `prepend`.
- **N2**: `[in] CBLAS_INT` number of elements in `append`.
- **append**: `[in] double` a [`Float64Array`][@stdlib/array/float64] containing values to append prior to computing differences..
- **strideA**: `[in] CBLAS_INT` strides length for `append`.
- **offsetA**: `[in] CBLAS_INT` starting index for `append`.
- **out**: `[in] double` output [`Float64Array`][@stdlib/array/float64].
- **strideOut**: `[in] CBLAS_INT` stride length for `out`.
- **offsetOut**: `[in] CBLAS_INT` starting index for `out`.
- **workspace**: `[in] double` workspace [`Float64Array`][@stdlib/array/float64].
- **strideW**: `[in] CBLAS_INT` stride length for `workspace`.
- **offsetW**: `[in] CBLAS_INT` starting index for `workspace`.

```c
void stdlib_strided_ddiff_ndarray( const CBLAS_INT N, const CBLAS_INT k, double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, const CBLAS_INT N1, double *prepend, const CBLAS_INT strideP, const CBLAS_INT offsetP, const CBLAS_INT N2, double *append, const CBLAS_INT strideA, const CBLAS_INT offsetA, double *out, const CBLAS_INT strideOut, const CBLAS_INT offsetOut, double *workspace, 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/ddiff.h"
#include <stdio.h>

int main( void ) {
// Create a strided array:
double x[] = { 1.0, -2.0, 3.0, -4.0, 5.0, -6.0, 7.0, -8.0 };

// Define prepend values:
double p[] = { -1.0 };

// Define append values:
double a[] = { 10.0 };

// Define output array:
double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

// Define workspace:
double w[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

// Fill the array:
stdlib_strided_ddiff( 8, 3, x, 1, 1, p, 1, 1, a, 1, out, 1, w, 1 );

// Print the result:
for ( int i = 0; i < 7; i++ ) {
printf( "out[ %i ] = %lf\n", i, out[ 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

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

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

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

</section>

<!-- /.links -->
Loading
Loading