feat: add blas/ext/base/gsort

PR-URL: #9712
Closes: stdlib-js/metr-issue-tracker#119
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: headlessNode

lib/node_modules/@stdlib/blas/ext/base/gsort/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.
+
+-->
+
+# gsort
+
+> Sort a strided array.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var gsort = require( '@stdlib/blas/ext/base/gsort' );
+```
+
+#### gsort( N, order, x, strideX )
+
+Sorts a strided array.
+
+```javascript
+var x = [ 1.0, -2.0, 3.0, -4.0 ];
+
+gsort( x.length, 1.0, x, 1 );
+// x => [ -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 [`Array`][mdn-array] or [`typed array`][mdn-typed-array].
+-   **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 x = [ 1.0, -2.0, 3.0, -4.0 ];
+
+gsort( 2, -1.0, x, 2 );
+// x => [ 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...
+gsort( 2, -1.0, x1, 2 );
+// x0 => <Float64Array>[ 1.0, 4.0, 3.0, 2.0 ]
+```
+
+#### gsort.ndarray( N, order, x, strideX, offsetX )
+
+Sorts a strided array using alternative indexing semantics.
+
+```javascript
+var x = [ 1.0, -2.0, 3.0, -4.0 ];
+
+gsort.ndarray( x.length, 1.0, x, 1, 0 );
+// x => [ -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 x = [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ];
+
+gsort.ndarray( 3, 1.0, x, 1, x.length-3 );
+// x => [ 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 gsort = require( '@stdlib/blas/ext/base/gsort' );
+
+var x = discreteUniform( 10, -100, 100, {
+    'dtype': 'generic'
+});
+console.log( x );
+
+gsort( x.length, -1.0, x, -1 );
+console.log( x );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- 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">
+
+[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+<!-- <related-links> -->
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/ext/base/gsort/benchmark/benchmark.unsorted_random.js

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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.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var floor = require( '@stdlib/math/base/special/floor' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var gsort = require( './../lib/main.js' );
+
+
+// FUNCTIONS //
+
+/**
+* Create a benchmark function.
+*
+* @private
+* @param {PositiveInteger} iter - number of iterations
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( iter, len ) {
+	var tmp;
+	var x;
+	var i;
+
+	x = [];
+	for ( i = 0; i < iter; i++ ) {
+		tmp = uniform( len, -100.0, 100.0, {
+			'dtype': 'generic'
+		});
+		x.push( tmp );
+	}
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var xc;
+		var y;
+		var i;
+
+		xc = x.slice();
+		for ( i = 0; i < iter; i++ ) {
+			xc[ i ] = x[ i ].slice();
+		}
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			y = gsort( len, 1, xc[ i ], 1 );
+			if ( isnan( y[ i%len ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnan( y[ i%len ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+function main() {
+	var opts;
+	var iter;
+	var len;
+	var min;
+	var max;
+	var f;
+	var i;
+
+	iter = 1e6;
+	min = 1; // 10^min
+	max = 4; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		len = pow( 10, i );
+		f = createBenchmark( iter, len );
+		opts = {
+			'iterations': iter
+		};
+		bench( format( '%s::unsorted,random:len=%d', pkg, len ), opts, f );
+		iter = floor( pow( iter, 3.0/4.0 ) );
+	}
+}
+
+main();