feat: add accessor arrays support to blas/ext/base/gcusumkbn

lib/node_modules/@stdlib/blas/ext/base/gcusumkbn/README.md

@@ -128,6 +128,7 @@ gcusumkbn.ndarray( 4, 0.0, x, 2, 1, y, -1, y.length-1 );
 ## Notes
 
 -   If `N <= 0`, both functions return `y` 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])
 -   Depending on the environment, the typed versions ([`dcusum`][@stdlib/blas/ext/base/dcusum], [`scusum`][@stdlib/blas/ext/base/scusum], etc.) are likely to be significantly more performant.
 
 </section>
@@ -198,6 +199,8 @@ console.log( y );
 
 [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/ext/base/dcusum]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/blas/ext/base/dcusum
 
 [@stdlib/blas/ext/base/scusum]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/blas/ext/base/scusum

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

@@ -20,7 +20,17 @@
 
 /// <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>;
+
+/**
+* Input array.
+*/
+type OutputArray = NumericArray | Collection<number> | AccessorArrayLike<number>;
 
 /**
 * Interface describing `gcusumkbn`.
@@ -44,7 +54,7 @@ interface Routine {
 	* gcusumkbn( x.length, 0.0, x, 1, y, 1 );
 	* // y => [ 1.0, -1.0, 1.0 ]
 	*/
-	( N: number, sum: number, x: NumericArray, strideX: number, y: NumericArray, strideY: number ): NumericArray;
+	( N: number, sum: number, x: InputArray, strideX: number, y: OutputArray, strideY: number ): OutputArray;
 
 	/**
 	* Computes the cumulative sum of strided array elements using an improved Kahan–Babuška algorithm and alternative indexing semantics.
@@ -66,7 +76,7 @@ interface Routine {
 	* gcusumkbn.ndarray( x.length, 0.0, x, 1, 0, y, 1, 0 );
 	* // y => [ 1.0, -1.0, 1.0 ]
 	*/
-	ndarray( N: number, sum: number, x: NumericArray, strideX: number, offsetX: number, y: NumericArray, strideY: number, offsetY: number ): NumericArray;
+	ndarray( N: number, sum: number, x: InputArray, strideX: number, offsetX: number, y: OutputArray, strideY: number, offsetY: number ): OutputArray;
 }
 
 /**

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

@@ -16,6 +16,7 @@
 * limitations under the License.
 */
 
+import AccessorArray = require( '@stdlib/array/base/accessor' );
 import gcusumkbn = require( './index' );
 
 
@@ -26,7 +27,8 @@ import gcusumkbn = require( './index' );
 	const x = new Float64Array( 10 );
 	const y = new Float64Array( 10 );
 
-	gcusumkbn( x.length, 0.0, x, 1, y, 1 ); // $ExpectType NumericArray
+	gcusumkbn( x.length, 0.0, x, 1, y, 1 ); // $ExpectType OutputArray
+	gcusumkbn( x.length, 0.0, new AccessorArray( x ), 1, new AccessorArray( y ), 1 ); // $ExpectType OutputArray
 }
 
 // The compiler throws an error if the function is provided a first argument which is not a number...
@@ -139,7 +141,8 @@ import gcusumkbn = require( './index' );
 	const x = new Float64Array( 10 );
 	const y = new Float64Array( 10 );
 
-	gcusumkbn.ndarray( x.length, 0.0, x, 1, 0, y, 1, 0 ); // $ExpectType NumericArray
+	gcusumkbn.ndarray( x.length, 0.0, x, 1, 0, y, 1, 0 ); // $ExpectType OutputArray
+	gcusumkbn.ndarray( x.length, 0.0, new AccessorArray( x ), 1, 0, new AccessorArray( y ), 1, 0 ); // $ExpectType OutputArray
 }
 
 // The compiler throws an error if the `ndarray` method is provided a first argument which is not a number...

lib/node_modules/@stdlib/blas/ext/base/gcusumkbn/lib/accessors.js

@@ -0,0 +1,107 @@
+/**
+* @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';
+
+// MODULES //
+
+var abs = require( '@stdlib/math/base/special/abs' );
+
+
+// MAIN //
+
+/**
+* Computes the cumulative sum of strided array elements using an improved Kahan–Babuška algorithm.
+*
+* ## Method
+*
+* -   This implementation uses an "improved Kahan–Babuška algorithm", as described by Neumaier (1974).
+*
+* ## References
+*
+* -   Neumaier, Arnold. 1974. "Rounding Error Analysis of Some Methods for Summing Finite Sums." _Zeitschrift Für Angewandte Mathematik Und Mechanik_ 54 (1): 39–51. doi:[10.1002/zamm.19740540106](https://doi.org/10.1002/zamm.19740540106).
+*
+* @private
+* @param {PositiveInteger} N - number of indexed elements
+* @param {number} sum - initial sum
+* @param {Object} x - input array object
+* @param {Collection} x.data - input array data
+* @param {Array<Function>} x.accessors - array element accessors
+* @param {integer} strideX - stride length for `x`
+* @param {NonNegativeInteger} offsetX - starting index for `x`
+* @param {Object} y - output array object
+* @param {Collection} y.data - output array data
+* @param {Array<Function>} y.accessors - array element accessors
+* @param {integer} strideY - stride length for `y`
+* @param {NonNegativeInteger} offsetY - starting index for `y`
+* @returns {Object} output array object
+*
+* @example
+* var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
+* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
+*
+* var x = toAccessorArray( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
+* var y = toAccessorArray( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
+*
+* gcusumkbn( 4, 0.0, arraylike2object( x ), 2, 1, arraylike2object( y ), 1, 0 );
+*/
+function gcusumkbn( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
+	var xbuf;
+	var ybuf;
+	var xget;
+	var yset;
+	var ix;
+	var iy;
+	var s;
+	var v;
+	var t;
+	var c;
+	var i;
+
+	// Cache reference to array data:
+	xbuf = x.data;
+	ybuf = y.data;
+
+	// Cache reference to the element accessors:
+	xget = x.accessors[ 0 ];
+	yset = y.accessors[ 1 ];
+
+	ix = offsetX;
+	iy = offsetY;
+	s = sum;
+	c = 0.0;
+	for ( i = 0; i < N; i++ ) {
+		v = xget( xbuf, ix );
+		t = s + v;
+		if ( abs( s ) >= abs( v ) ) {
+			c += (s-t) + v;
+		} else {
+			c += (v-t) + s;
+		}
+		s = t;
+		yset( ybuf, iy, s + c );
+		ix += strideX;
+		iy += strideY;
+	}
+	return y;
+}
+
+
+// EXPORTS //
+
+module.exports = gcusumkbn;

lib/node_modules/@stdlib/blas/ext/base/gcusumkbn/lib/ndarray.js

@@ -20,7 +20,9 @@
 
 // MODULES //
 
+var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
 var abs = require( '@stdlib/math/base/special/abs' );
+var accessors = require( './accessors.js' );
 
 
 // MAIN //
@@ -56,6 +58,8 @@ var abs = require( '@stdlib/math/base/special/abs' );
 function gcusumkbn( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
 	var ix;
 	var iy;
+	var ox;
+	var oy;
 	var s;
 	var v;
 	var t;
@@ -65,6 +69,11 @@ function gcusumkbn( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
 	if ( N <= 0 ) {
 		return y;
 	}
+	ox = arraylike2object( x );
+	oy = arraylike2object( y );
+	if ( ox.accessorProtocol || oy.accessorProtocol ) {
+		return accessors( N, sum, ox, strideX, offsetX, oy, strideY, offsetY );
+	}
 	ix = offsetX;
 	iy = offsetY;
 	s = sum;