npm package: @stdlib/blas-ext-base-dsort
Description: Sort a double-precision floating-point strided array.
Author: The Stdlib Authors
Latest version: 0.1.1

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# dsort

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> Sort a double-precision floating-point strided array.

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### dsort( N, order, x, strideX )

Sorts a double-precision floating-point strided array.

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

var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0 ] );

dsort( x.length, 1.0, x, 1 );
// x => <Float64Array>[ -4.0, -2.0, 1.0, 3.0 ]
```

The function has the following parameters:

-   **N**: number of indexed elements.
-   **order**: sort order. If `order < 0.0`, the input strided array is sorted in **decreasing** order. If `order > 0.0`, the input strided array is sorted in **increasing** order. If `order == 0.0`, the input strided array is left unchanged.
-   **x**: input [`Float64Array`][@stdlib/array/float64].
-   **strideX**: stride length.

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

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

var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0 ] );

dsort( 2, -1.0, x, 2 );
// x => <Float64Array>[ 3.0, -2.0, 1.0, -4.0 ]
```

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( [ 1.0, 2.0, 3.0, 4.0 ] );

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

// Sort every other element...
dsort( 2, -1.0, x1, 2 );
// x0 => <Float64Array>[ 1.0, 4.0, 3.0, 2.0 ]
```

#### dsort.ndarray( N, order, x, strideX, offsetX )

Sorts a double-precision floating-point strided array using alternative indexing semantics.

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

var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0 ] );

dsort.ndarray( x.length, 1.0, x, 1, 0 );
// x => <Float64Array>[ -4.0, -2.0, 1.0, 3.0 ]
```

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 only the last three elements:

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

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

dsort.ndarray( 3, 1.0, x, 1, 3 );
// x => <Float64Array>[ 1.0, -2.0, 3.0, -6.0, -4.0, 5.0 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If `N <= 0` or `order == 0.0`, both functions return `x` unchanged.
-   The algorithm distinguishes between `-0` and `+0`. When sorted in increasing order, `-0` is sorted before `+0`. When sorted in decreasing order, `-0` is sorted after `+0`.
-   The algorithm sorts `NaN` values to the end. When sorted in increasing order, `NaN` values are sorted last. When sorted in decreasing order, `NaN` values are sorted first.
-   The input strided array is sorted **in-place** (i.e., the input strided array is **mutated**).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

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

dsort( x.length, 1.0, x, 1 );
console.log( x );
```

</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/dsort.h"
```

#### stdlib_strided_dsort( N, order, \*X, strideX )

Sorts a double-precision floating-point strided array.

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

stdlib_strided_dsort( 4, 1.0, x, 1 );
```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.
-   **order**: `[in] double` sort order. If `order < 0.0`, the input strided array is sorted in **decreasing** order. If `order > 0.0`, the input strided array is sorted in **increasing** order. If `order == 0.0`, the input strided array is left unchanged.
-   **X**: `[inout] double*` input array.
-   **strideX**: `[in] CBLAS_INT` stride length for `X`.

```c
void stdlib_strided_dsort( const CBLAS_INT N, const double order, double *X, const CBLAS_INT strideX );
```

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

#### stdlib_strided_dsort_ndarray( N, order, \*X, strideX, offsetX )

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

Sorts a double-precision floating-point strided array using alternative indexing semantics.

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

stdlib_strided_dsort_ndarray( 4, 1.0, x, 1, 0 );
```

The function accepts the following arguments:

-   **N**: `[in] CBLAS_INT` number of indexed elements.
-   **order**: `[in] double` sort order. If `order < 0.0`, the input strided array is sorted in **decreasing** order. If `order > 0.0`, the input strided array is sorted in **increasing** order. If `order == 0.0`, the input strided array is left unchanged.
-   **X**: `[inout] double*` input array.
-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.

```c
void stdlib_strided_dsort_ndarray( const CBLAS_INT N, const double order, double *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/dsort.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 };

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

    // Specify the stride length:
    const int strideX = 1;

    // Sort the array:
    stdlib_strided_dsort( N, 1.0, x, strideX );

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

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<section class="references">

</section>

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<section class="related">

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<section class="main-repo" >

* * *

## Notice

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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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