feat: add blas/ext/base/gswap-columns

lib/node_modules/@stdlib/blas/ext/base/gswap-columns/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.
+
+-->
+
+# gswapColumns
+
+> Interchange two columns in a matrix `A`.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var gswapColumns = require( '@stdlib/blas/ext/base/gswap-columns' );
+```
+
+#### gswapColumns( order, M, N, i, j, A, LDA )
+
+Interchanges two columns in a matrix `A`.
+
+```javascript
+/*
+    A = [
+        [ 1.0, 2.0 ],
+        [ 3.0, 4.0 ],
+        [ 5.0, 6.0 ]
+    ]
+*/
+var A = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gswapColumns( 'row-major', 3, 2, 0, 1, A, 2 );
+// A => [ 2.0, 1.0, 4.0, 3.0, 6.0, 5.0 ]
+```
+
+The function has the following parameters:
+
+-   **order**: storage layout.
+-   **M**: number of rows in `A`.
+-   **N**: number of columns in `A`.
+-   **i**: index of the first column to interchange.
+-   **j**: index of the second column to interchange.
+-   **A**: input matrix as a linear array.
+-   **LDA**: stride length for the first dimension of `A` (a.k.a., leading dimension of the matrix `A`).
+
+Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
+
+<!-- eslint-disable stdlib/capitalized-comments -->
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+
+// Initial array...
+var A0 = new Float64Array( [ 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
+
+// Create an offset view...
+var A1 = new Float64Array( A0.buffer, A0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+
+// Interchange the first and second columns...
+gswapColumns( 'row-major', 3, 2, 0, 1, A1, 2 );
+// A0 => <Float64Array>[ 0.0, 2.0, 1.0, 4.0, 3.0, 6.0, 5.0 ]
+```
+
+#### gswapColumns.ndarray( M, N, i, j, A, sa1, sa2, oa )
+
+Interchanges two columns in a matrix `A` using alternative indexing semantics.
+
+```javascript
+/*
+    A = [
+        [ 1.0, 2.0 ],
+        [ 3.0, 4.0 ],
+        [ 5.0, 6.0 ]
+    ]
+*/
+var A = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gswapColumns.ndarray( 3, 2, 0, 1, A, 2, 1, 0 );
+// A => [ 2.0, 1.0, 4.0, 3.0, 6.0, 5.0 ]
+```
+
+The function has the following parameters:
+
+-   **M**: number of rows in `A`.
+-   **N**: number of columns in `A`.
+-   **i**: index of the first column to interchange.
+-   **j**: index of the second column to interchange.
+-   **A**: input matrix as a linear array.
+-   **sa1**: stride length for the first dimension of `A`.
+-   **sa2**: stride length for the second dimension of `A`.
+-   **oa**: starting index for `A`.
+
+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,
+
+```javascript
+/*
+    A = [
+        [ 1.0, 2.0 ],
+        [ 3.0, 4.0 ],
+        [ 5.0, 6.0 ]
+    ]
+*/
+var A = [ 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gswapColumns.ndarray( 3, 2, 0, 1, A, 2, 1, 1 );
+// A => [ 0.0, 2.0, 1.0, 4.0, 3.0, 6.0, 5.0 ]
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If provided negative column indices, both functions resolve the indices relative to the last column, with the last column corresponding to `-1`.
+-   Both functions mutate the input matrix `A`.
+-   Both functions support array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array/base/accessor`][@stdlib/array/base/accessor]).
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var ndarray2array = require( '@stdlib/ndarray/base/to-array' );
+var uniform = require( '@stdlib/random/array/discrete-uniform' );
+var numel = require( '@stdlib/ndarray/base/numel' );
+var shape2strides = require( '@stdlib/ndarray/base/shape2strides' );
+var gswapColumns = require( '@stdlib/blas/ext/base/gswap-columns' );
+
+var shape = [ 5, 8 ];
+var order = 'row-major';
+var strides = shape2strides( shape, order );
+
+var N = numel( shape );
+
+var A = uniform( N, -10, 10, {
+    'dtype': 'generic'
+});
+console.log( ndarray2array( A, shape, strides, 0, order ) );
+
+gswapColumns( order, shape[ 0 ], shape[ 1 ], 0, -1, A, strides[ 0 ] );
+console.log( ndarray2array( A, shape, strides, 0, order ) );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<section class="links">
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+[@stdlib/array/base/accessor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/base/accessor
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/ext/base/gswap-columns/benchmark/benchmark.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 isnan = require( '@stdlib/math/base/assert/is-nan' );
+var zeros = require( '@stdlib/array/zeros' );
+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 gswapColumns = require( './../lib' );
+
+
+// VARIABLES //
+
+var LAYOUTS = [
+	'row-major',
+	'column-major'
+];
+
+
+// FUNCTIONS //
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {string} order - storage layout
+* @param {PositiveInteger} N - number of elements along each dimension
+* @returns {Function} benchmark function
+*/
+function createBenchmark( order, N ) {
+	var A = zeros( N*N, 'generic' );
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var z;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			z = gswapColumns( order, N, N, 0, N-1, A, N );
+			if ( isnan( z[ i%z.length ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnan( z[ i%z.length ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var min;
+	var max;
+	var ord;
+	var N;
+	var f;
+	var i;
+	var k;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( k = 0; k < LAYOUTS.length; k++ ) {
+		ord = LAYOUTS[ k ];
+		for ( i = min; i <= max; i++ ) {
+			N = floor( pow( pow( 10, i ), 1.0/2.0 ) );
+			f = createBenchmark( ord, N );
+			bench( format( '%s::square_matrix:order=%s,size=%d', pkg, ord, N*N ), f );
+		}
+	}
+}
+
+main();