feat: add accessor arrays support to blas/ext/base/gapxsumkbn2

lib/node_modules/@stdlib/blas/ext/base/gapxsumkbn2/README.md

@@ -109,6 +109,7 @@ var v = gapxsumkbn2.ndarray( 4, 5.0, x, 2, 1 );
 ## Notes
 
 -   If `N <= 0`, both functions return `0.0`.
+-   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 ([`dapxsumkbn2`][@stdlib/blas/ext/base/dapxsumkbn2], [`sapxsumkbn2`][@stdlib/blas/ext/base/sapxsumkbn2], etc.) are likely to be significantly more performant.
 
 </section>
@@ -175,6 +176,8 @@ console.log( v );
 
 [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
+
 [@klein:2005a]: https://doi.org/10.1007/s00607-005-0139-x
 
 <!-- <related-links> -->

lib/node_modules/@stdlib/blas/ext/base/gapxsumkbn2/docs/types/index.d.ts

@@ -20,7 +20,11 @@
 
 /// <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 `gapxsumkbn2`.
@@ -41,7 +45,7 @@ interface Routine {
 	* var v = gapxsumkbn2( x.length, 5.0, x, 1 );
 	* // returns 16.0
 	*/
-	( N: number, alpha: number, x: NumericArray, strideX: number ): number;
+	( N: number, alpha: number, x: InputArray, strideX: number ): number;
 
 	/**
 	* Adds a scalar constant to each strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm and alternative indexing semantics.
@@ -59,7 +63,7 @@ interface Routine {
 	* var v = gapxsumkbn2.ndarray( x.length, 5.0, x, 1, 0 );
 	* // returns 16.0
 	*/
-	ndarray( N: number, alpha: number, x: NumericArray, strideX: number, offsetX: number ): number;
+	ndarray( N: number, alpha: number, x: InputArray, strideX: number, offsetX: number ): number;
 }
 
 /**

lib/node_modules/@stdlib/blas/ext/base/gapxsumkbn2/docs/types/test.ts

@@ -16,6 +16,7 @@
 * limitations under the License.
 */
 
+import AccessorArray = require( '@stdlib/array/base/accessor' );
 import gapxsumkbn2 = require( './index' );
 
 
@@ -26,6 +27,7 @@ import gapxsumkbn2 = require( './index' );
 	const x = new Float64Array( 10 );
 
 	gapxsumkbn2( x.length, 5.0, x, 1 ); // $ExpectType number
+	gapxsumkbn2( x.length, 5.0, new AccessorArray( x ), 1 ); // $ExpectType number
 }
 
 // The compiler throws an error if the function is provided a first argument which is not a number...
@@ -100,6 +102,7 @@ import gapxsumkbn2 = require( './index' );
 	const x = new Float64Array( 10 );
 
 	gapxsumkbn2.ndarray( x.length, 5.0, x, 1, 0 ); // $ExpectType number
+	gapxsumkbn2.ndarray( x.length, 5.0, new AccessorArray( x ), 1, 0 ); // $ExpectType 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/ext/base/gapxsumkbn2/lib/accessors.js

@@ -0,0 +1,109 @@
+/**
+* @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 //
+
+/**
+* Adds a scalar constant to each strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.
+*
+* ## Method
+*
+* -   This implementation uses a second-order iterative Kahan–Babuška algorithm, as described by Klein (2005).
+*
+* ## References
+*
+* -   Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." _Computing_ 76 (3): 279–93. doi:[10.1007/s00607-005-0139-x](https://doi.org/10.1007/s00607-005-0139-x).
+*
+* @private
+* @param {PositiveInteger} N - number of indexed elements
+* @param {number} alpha - scalar constant
+* @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
+* @param {NonNegativeInteger} offsetX - starting index
+* @returns {number} sum
+*
+* @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 v = gapxsumkbn2( 4, 5.0, arraylike2object( x ), 2, 1 );
+* // returns 25.0
+*/
+function gapxsumkbn2( N, alpha, x, strideX, offsetX ) {
+	var xbuf;
+	var get;
+	var sum;
+	var ccs;
+	var ix;
+	var cs;
+	var cc;
+	var v;
+	var t;
+	var c;
+	var i;
+
+	// Cache reference to array data:
+	xbuf = x.data;
+
+	// Cache a reference to the element accessor:
+	get = x.accessors[ 0 ];
+
+	ix = offsetX;
+	if ( strideX === 0 ) {
+		return N * ( alpha + get( xbuf, ix ) );
+	}
+	sum = 0.0;
+	ccs = 0.0; // second order correction term for lost low order bits
+	cs = 0.0; // first order correction term for lost low order bits
+	for ( i = 0; i < N; i++ ) {
+		v = alpha + get( xbuf, ix );
+		t = sum + v;
+		if ( abs( sum ) >= abs( v ) ) {
+			c = (sum-t) + v;
+		} else {
+			c = (v-t) + sum;
+		}
+		sum = t;
+		t = cs + c;
+		if ( abs( cs ) >= abs( c ) ) {
+			cc = (cs-t) + c;
+		} else {
+			cc = (c-t) + cs;
+		}
+		cs = t;
+		ccs += cc;
+		ix += strideX;
+	}
+	return sum + cs + ccs;
+}
+
+
+// EXPORTS //
+
+module.exports = gapxsumkbn2;

lib/node_modules/@stdlib/blas/ext/base/gapxsumkbn2/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 //
@@ -58,11 +60,16 @@ function gapxsumkbn2( N, alpha, x, strideX, offsetX ) {
 	var v;
 	var t;
 	var c;
+	var o;
 	var i;
 
 	if ( N <= 0 ) {
 		return 0.0;
 	}
+	o = arraylike2object( x );
+	if ( o.accessorProtocol ) {
+		return accessors( N, alpha, o, strideX, offsetX );
+	}
 	ix = offsetX;
 	if ( strideX === 0 ) {
 		return N * ( alpha + x[ ix ] );

lib/node_modules/@stdlib/blas/ext/base/gapxsumkbn2/test/test.main.js

@@ -21,8 +21,8 @@
 // MODULES //
 
 var tape = require( 'tape' );
-var floor = require( '@stdlib/math/base/special/floor' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var Float64Array = require( '@stdlib/array/float64' );
 var gapxsumkbn2 = require( './../lib' );
 
@@ -67,6 +67,33 @@ tape( 'the function adds a constant and calculates the sum of all strided array
 	t.end();
 });
 
+tape( 'the function adds a constant and calculates the sum of all strided array elements (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0, 0.0, -3.0, 3.0 ];
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 1 );
+	t.strictEqual( v, 48.0, 'returns expected value' );
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0 ];
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 1 );
+	t.strictEqual( v, 33.0, 'returns expected value' );
+
+	x = [ -4.0, -4.0 ];
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 1 );
+	t.strictEqual( v, 2.0, 'returns expected value' );
+
+	x = [ NaN, 4.0 ];
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 1 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	x = [ 1.0, 1e100, 1.0, -1.0e100 ];
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 1 );
+	t.strictEqual( v, 12.0, 'returns expected value' );
+
+	t.end();
+});
+
 tape( 'if provided an `N` parameter less than or equal to `0`, the function returns `0.0`', function test( t ) {
 	var x;
 	var v;
@@ -95,7 +122,6 @@ tape( 'if provided an `N` parameter equal to `1`, the function returns the first
 });
 
 tape( 'the function supports a `stride` parameter', function test( t ) {
-	var N;
 	var x;
 	var v;
 
@@ -110,15 +136,34 @@ tape( 'the function supports a `stride` parameter', function test( t ) {
 		2.0
 	];
 
-	N = floor( x.length / 2 );
-	v = gapxsumkbn2( N, 5.0, x, 2 );
+	v = gapxsumkbn2( 4, 5.0, x, 2 );
+
+	t.strictEqual( v, 25.0, 'returns expected value' );
+	t.end();
+});
+
+tape( 'the function supports a `stride` parameter (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		1.0,  // 0
+		2.0,
+		2.0,  // 1
+		-7.0,
+		-2.0, // 2
+		3.0,
+		4.0,  // 3
+		2.0
+	];
+
+	v = gapxsumkbn2( 4, 5.0, toAccessorArray( x ), 2 );
 
 	t.strictEqual( v, 25.0, 'returns expected value' );
 	t.end();
 });
 
 tape( 'the function supports a negative `stride` parameter', function test( t ) {
-	var N;
 	var x;
 	var v;
 
@@ -133,8 +178,28 @@ tape( 'the function supports a negative `stride` parameter', function test( t )
 		2.0
 	];
 
-	N = floor( x.length / 2 );
-	v = gapxsumkbn2( N, 5.0, x, -2 );
+	v = gapxsumkbn2( 4, 5.0, x, -2 );
+
+	t.strictEqual( v, 25.0, 'returns expected value' );
+	t.end();
+});
+
+tape( 'the function supports a negative `stride` parameter (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		1.0,  // 3
+		2.0,
+		2.0,  // 2
+		-7.0,
+		-2.0, // 1
+		3.0,
+		4.0,  // 0
+		2.0
+	];
+
+	v = gapxsumkbn2( 4, 5.0, toAccessorArray( x ), -2 );
 
 	t.strictEqual( v, 25.0, 'returns expected value' );
 	t.end();
@@ -152,10 +217,21 @@ tape( 'if provided a `stride` parameter equal to `0`, the function returns the f
 	t.end();
 });
 
+tape( 'if provided a `stride` parameter equal to `0`, the function returns the first element plus a constant repeated N times (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
+
+	v = gapxsumkbn2( x.length, 5.0, toAccessorArray( x ), 0 );
+	t.strictEqual( v, x.length * (x[0]+5.0), 'returns expected value' );
+
+	t.end();
+});
+
 tape( 'the function supports view offsets', function test( t ) {
 	var x0;
 	var x1;
-	var N;
 	var v;
 
 	x0 = new Float64Array([
@@ -171,9 +247,8 @@ tape( 'the function supports view offsets', function test( t ) {
 	]);
 
 	x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
-	N = floor(x1.length / 2);
 
-	v = gapxsumkbn2( N, 5.0, x1, 2 );
+	v = gapxsumkbn2( 4, 5.0, x1, 2 );
 	t.strictEqual( v, 25.0, 'returns expected value' );
 
 	t.end();