feat: add accessor array support to blas/base/gscal

PR-URL: #5418
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: headlessNode

lib/node_modules/@stdlib/blas/base/gscal/README.md

@@ -109,6 +109,7 @@ gscal.ndarray( 3, 5.0, x, 1, x.length-3 );
 
 -   If `N <= 0`, both functions return `x` unchanged.
 -   `gscal()` corresponds to the [BLAS][blas] level 1 function [`dscal`][dscal] with the exception that this implementation works with any array type, not just Float64Arrays. Depending on the environment, the typed versions ([`dscal`][@stdlib/blas/base/dscal], [`sscal`][@stdlib/blas/base/sscal], etc.) are likely to be significantly more performant.
+-   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>
 
@@ -166,6 +167,8 @@ console.log( x );
 
 [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
+
 [@stdlib/blas/base/dscal]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/blas/base/dscal
 
 [@stdlib/blas/base/sscal]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/blas/base/sscal

lib/node_modules/@stdlib/blas/base/gscal/docs/types/index.d.ts

@@ -20,7 +20,12 @@
 
 /// <reference types="@stdlib/types"/>
 
-import { NumericArray } from '@stdlib/types/array';
+import { NumericArray, Collection, AccessorArrayLike } from '@stdlib/types/array';
+
+/**
+* Input array.
+*/
+type InputArray = NumericArray | Collection<number> | AccessorArrayLike<number>;
 
 /**
 * Interface describing `gscal`.
@@ -41,7 +46,7 @@ interface Routine {
 	* gscal( x.length, 5.0, x, 1 );
 	* // x => [ -10.0, 5.0, 15.0, -25.0, 20.0, 0.0, -5.0, -15.0 ]
 	*/
-	( N: number, alpha: number, x: NumericArray, stride: number ): NumericArray;
+	<T extends InputArray>( N: number, alpha: number, x: T, stride: number ): T;
 
 	/**
 	* Multiplies a vector `x` by a constant `alpha` using alternative indexing semantics.
@@ -59,7 +64,7 @@ interface Routine {
 	* gscal.ndarray( x.length, 5.0, x, 1, 0 );
 	* // x => [ -10.0, 5.0, 15.0, -25.0, 20.0, 0.0, -5.0, -15.0 ]
 	*/
-	ndarray( N: number, alpha: number, x: NumericArray, stride: number, offset: number ): NumericArray;
+	ndarray<T extends InputArray>( N: number, alpha: number, x: T, stride: number, offset: number ): T;
 }
 
 /**

lib/node_modules/@stdlib/blas/base/gscal/docs/types/test.ts

@@ -16,6 +16,7 @@
 * limitations under the License.
 */
 
+import AccessorArray = require( '@stdlib/array/base/accessor' );
 import gscal = require( './index' );
 
 
@@ -25,7 +26,8 @@ import gscal = require( './index' );
 {
 	const x = new Float64Array( 10 );
 
-	gscal( x.length, 5.0, x, 1 ); // $ExpectType NumericArray
+	gscal( x.length, 5.0, x, 1 ); // $ExpectType Float64Array
+	gscal( x.length, 5.0, new AccessorArray( x ), 1 ); // $ExpectType AccessorArray<number>
 }
 
 // The compiler throws an error if the function is provided a first argument which is not a number...
@@ -100,7 +102,8 @@ import gscal = require( './index' );
 {
 	const x = new Float64Array( 10 );
 
-	gscal.ndarray( x.length, 5.0, x, 1, 0 ); // $ExpectType NumericArray
+	gscal.ndarray( x.length, 5.0, x, 1, 0 ); // $ExpectType Float64Array
+	gscal.ndarray( x.length, 5.0, new AccessorArray( x ), 1, 0 ); // $ExpectType AccessorArray<number>
 }
 
 // The compiler throws an error if the `ndarray` method is provided a first argument which is not a number...

lib/node_modules/@stdlib/blas/base/gscal/lib/accessors.js

@@ -0,0 +1,101 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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';
+
+// VARIABLES //
+
+var M = 5;
+
+
+// MAIN //
+
+/**
+* Multiplies `x` by a scalar `alpha`.
+*
+* @param {PositiveInteger} N - number of indexed elements
+* @param {number} alpha - scalar
+* @param {Object} x - input array object
+* @param {Collection} x.data - input array data
+* @param {Array<Function>} x.accessors - array element accessors
+* @param {integer} stride - index increment
+* @param {NonNegativeInteger} offset - starting index
+* @returns {NumericArray} input array
+*
+* @example
+* var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
+* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
+*
+* var x = [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ];
+*
+* gscal( 3, 5.0, arraylike2object( toAccessorArray( x ) ), 1, x.length-3 );
+* // x => [ 1.0, -2.0, 3.0, -20.0, 25.0, -30.0 ]
+*/
+function gscal( N, alpha, x, stride, offset ) {
+	var xbuf;
+	var xget;
+	var xset;
+	var ix;
+	var m;
+	var i;
+
+	xbuf = x.data;
+	xget = x.accessors[ 0 ];
+	xset = x.accessors[ 1 ];
+
+	ix = offset;
+	if ( stride === 0 ) {
+		xset( xbuf, ix, xget( xbuf, ix ) * N * alpha );
+		return x;
+	}
+
+	// Use loop unrolling if the stride is equal to `1`...
+	if ( stride === 1 ) {
+		m = N % M;
+
+		// If we have a remainder, run a clean-up loop...
+		if ( m > 0 ) {
+			for ( i = 0; i < m; i++ ) {
+				xset( xbuf, ix, xget( xbuf, ix ) * alpha );
+				ix += stride;
+			}
+		}
+		if ( N < M ) {
+			return x;
+		}
+		for ( i = m; i < N; i += M ) {
+			xset( xbuf, ix, xget( xbuf, ix ) * alpha );
+			xset( xbuf, ix+1, xget( xbuf, ix+1 ) * alpha );
+			xset( xbuf, ix+2, xget( xbuf, ix+2 ) * alpha );
+			xset( xbuf, ix+3, xget( xbuf, ix+3 ) * alpha );
+			xset( xbuf, ix+4, xget( xbuf, ix+4 ) * alpha );
+			ix += M;
+		}
+		return x;
+	}
+	for ( i = 0; i < N; i++ ) {
+		xset( xbuf, ix, xget( xbuf, ix ) * alpha );
+		ix += stride;
+	}
+	return x;
+}
+
+
+// EXPORTS //
+
+module.exports = gscal;

lib/node_modules/@stdlib/blas/base/gscal/lib/main.js

@@ -18,9 +18,10 @@
 
 'use strict';
 
-// VARIABLES //
+// MODULES //
 
-var M = 5;
+var stride2offset = require( '@stdlib/strided/base/stride2offset' );
+var ndarray = require( './ndarray.js' );
 
 
 // MAIN //
@@ -41,39 +42,7 @@ var M = 5;
 * // x => [ -10.0, 5.0, 15.0, -25.0, 20.0, 0.0, -5.0, -15.0 ]
 */
 function gscal( N, alpha, x, stride ) {
-	var m;
-	var i;
-
-	if ( N <= 0 || stride <= 0|| alpha === 1.0 ) {
-		return x;
-	}
-	// Use loop unrolling if the stride is equal to `1`...
-	if ( stride === 1 ) {
-		m = N % M;
-
-		// If we have a remainder, run a clean-up loop...
-		if ( m > 0 ) {
-			for ( i = 0; i < m; i += 1 ) {
-				x[ i ] *= alpha;
-			}
-		}
-		if ( N < M ) {
-			return x;
-		}
-		for ( i = m; i < N; i += M ) {
-			x[ i ] *= alpha;
-			x[ i+1 ] *= alpha;
-			x[ i+2 ] *= alpha;
-			x[ i+3 ] *= alpha;
-			x[ i+4 ] *= alpha;
-		}
-		return x;
-	}
-	N *= stride;
-	for ( i = 0; i < N; i += stride ) {
-		x[ i ] *= alpha;
-	}
-	return x;
+	return ndarray( N, alpha, x, stride, stride2offset( N, stride ) );
 }
 
 

lib/node_modules/@stdlib/blas/base/gscal/lib/ndarray.js

@@ -18,6 +18,12 @@
 
 'use strict';
 
+// MODULES //
+
+var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
+var accessors = require( './accessors.js' );
+
+
 // VARIABLES //
 
 var M = 5;
@@ -44,12 +50,23 @@ var M = 5;
 function gscal( N, alpha, x, stride, offset ) {
 	var ix;
 	var m;
+	var o;
 	var i;
 
 	if ( N <= 0 || alpha === 1.0 ) {
 		return x;
 	}
+	o = arraylike2object( x );
+	if ( o.accessorProtocol ) {
+		accessors( N, alpha, o, stride, offset );
+		return x;
+	}
+
 	ix = offset;
+	if ( stride === 0 ) {
+		x[ ix ] *= alpha * N;
+		return x;
+	}
 
 	// Use loop unrolling if the stride is equal to `1`...
 	if ( stride === 1 ) {
@@ -66,11 +83,12 @@ function gscal( N, alpha, x, stride, offset ) {
 			return x;
 		}
 		for ( i = m; i < N; i += M ) {
-			x[ i ] *= alpha;
-			x[ i+1 ] *= alpha;
-			x[ i+2 ] *= alpha;
-			x[ i+3 ] *= alpha;
-			x[ i+4 ] *= alpha;
+			x[ ix ] *= alpha;
+			x[ ix+1 ] *= alpha;
+			x[ ix+2 ] *= alpha;
+			x[ ix+3 ] *= alpha;
+			x[ ix+4 ] *= alpha;
+			ix += M;
 		}
 		return x;
 	}