feat: add blas/ext/base/gfill-diagonal

lib/node_modules/@stdlib/blas/ext/base/gfill-diagonal/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.
+
+-->
+
+# gfill-diagonal
+
+> Fill the diagonal of a matrix with a specified scalar constant.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var gfillDiagonal = require( '@stdlib/blas/ext/base/gfill-diagonal' );
+```
+
+#### gfillDiagonal( order, M, N, k, alpha, A, LDA )
+
+Fills the diagonal of a matrix with a specified scalar constant.
+
+```javascript
+var x = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gfillDiagonal( 'row-major', 2, 3, 0, 5.0, x, 3 );
+// x => [ 5.0, 2.0, 3.0, 4.0, 5.0, 6.0 ]
+```
+
+The function has the following parameters:
+
+-   **order**: storage layout.
+-   **M**: number of rows in `A`.
+-   **N**: number of columns in `A`.
+-   **k**: diagonal offset.
+-   **alpha**: scalar constant.
+-   **A**: input matrix as a linear array.
+-   **LDA**: stride of the first dimension of `A` (a.k.a., leading dimension of the matrix `A`).
+
+The `order` and `LDA` parameters determine the matrix layout. For example, to fill an upper diagonal:
+
+```javascript
+var A = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gfillDiagonal( 'row-major', 2, 3, 1, 7.0, A, 3 );
+// A => [ 1.0, 7.0, 3.0, 4.0, 5.0, 7.0 ]
+```
+
+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 matrix...
+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
+
+// Fill main diagonal...
+gfillDiagonal( 'row-major', 2, 3, 0, 8.0, A1, 3 );
+// A0 => <Float64Array>[ 0.0, 8.0, 2.0, 3.0, 4.0, 8.0, 6.0 ]
+```
+
+#### gfillDiagonal.ndarray( M, N, k, alpha, A, strideA1, strideA2, offsetA )
+
+Fills the diagonal of a matrix with a specified scalar constant using alternative indexing semantics.
+
+```javascript
+var A = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gfillDiagonal.ndarray( 2, 3, 0, 5.0, A, 3, 1, 0 );
+// A => [ 5.0, 2.0, 3.0, 4.0, 5.0, 6.0 ]
+```
+
+The function has the following parameters:
+
+-   **M**: number of rows in `A`.
+-   **N**: number of columns in `A`.
+-   **k**: diagonal offset.
+-   **alpha**: scalar constant.
+-   **A**: input matrix as a linear array.
+-   **strideA1**: stride of the first dimension of `A`.
+-   **strideA2**: stride of the second dimension of `A`.
+-   **offsetA**: 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, with an offset:
+
+```javascript
+var A = [ 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
+
+gfillDiagonal.ndarray( 2, 3, 0, 8.0, A, 3, 1, 1 );
+// A => [ 0.0, 8.0, 2.0, 3.0, 4.0, 8.0, 6.0 ]
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If `M <= 0` or `N <= 0`, both functions return `A` unchanged.
+-   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 uniform = require( '@stdlib/random/array/uniform' );
+var gfillDiagonal = require( '@stdlib/blas/ext/base/gfill-diagonal' );
+
+var A = uniform( 6, -100, 100, {
+    'dtype': 'float64'
+});
+console.log( A );
+
+gfillDiagonal( 'row-major', 2, 3, 0, 5.0, A, 3 );
+console.log( A );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- 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-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
+
+<!-- <related-links> -->
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/ext/base/gfill-diagonal/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 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 sqrt = require( '@stdlib/math/base/special/sqrt' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var gfillDiagonal = require( './../lib/main.js' );
+
+
+// VARIABLES //
+
+var options = {
+	'dtype': 'generic'
+};
+
+var LAYOUTS = [
+	'row-major',
+	'column-major'
+];
+
+
+// FUNCTIONS //
+
+/**
+* Create a benchmark function.
+*
+* @private
+* @param {string} order - storage layout order
+* @param {PositiveInteger} size - matrix size (N where matrix is NxN)
+* @returns {Function} benchmark function
+*/
+function createBenchmark( order, size ) {
+	var A = uniform( size * size, -100, 100, options );
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var y;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			y = gfillDiagonal( order, size, size, 0, i, A, size );
+			if ( isnan( y[ 0 ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnan( y[ 0 ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var size;
+	var min;
+	var max;
+	var ord;
+	var f;
+	var i;
+	var k;
+
+	min = 1; // 10^min
+	max = 3; // 10^max
+
+	for ( k = 0; k < LAYOUTS.length; k++ ) {
+		ord = LAYOUTS[ k ];
+		for ( i = min; i <= max; i++ ) {
+			size = floor( sqrt( pow( 10, i ) ) );
+			f = createBenchmark( ord, size );
+			bench( format( '%s::square_matrix:order=%s,size=%d', pkg, ord, size*size ), f );
+		}
+	}
+}
+
+main();