fix: update implementation to preserve signed zeros

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: passed
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: passed
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: na
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: kgryte

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

@@ -83,16 +83,19 @@ function gcusumpw( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
 	xbuf = x.data;
 	ybuf = y.data;
 
-	// Cache reference to the element accessors:
+	// Cache references to the element accessors:
 	xget = x.accessors[ 0 ];
 	yget = y.accessors[ 0 ];
 	yset = y.accessors[ 1 ];
 
 	ix = offsetX;
 	iy = offsetY;
 	if ( N <= BLOCKSIZE ) {
-		s = 0.0;
-		for ( i = 0; i < N; i++ ) {
+		s = xget( xbuf, ix );
+		yset( ybuf, iy, sum + s);
+		ix += strideX;
+		iy += strideY;
+		for ( i = 1; i < N; i++ ) {
 			s += xget( xbuf, ix );
 			yset( ybuf, iy, sum + s);
 			ix += strideX;

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

@@ -82,8 +82,11 @@ function gcusumpw( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
 	ix = offsetX;
 	iy = offsetY;
 	if ( N <= BLOCKSIZE ) {
-		s = 0.0;
-		for ( i = 0; i < N; i++ ) {
+		s = x[ ix ];
+		y[ iy ] = sum + s;
+		ix += strideX;
+		iy += strideY;
+		for ( i = 1; i < N; i++ ) {
 			s += x[ ix ];
 			y[ iy ] = sum + s;
 			ix += strideX;

lib/node_modules/@stdlib/blas/ext/base/gcusumpw/test/test.ndarray.js

@@ -16,12 +16,15 @@
 * limitations under the License.
 */
 
+/* eslint-disable max-len */
+
 'use strict';
 
 // MODULES //
 
 var tape = require( 'tape' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var isSameArray = require( '@stdlib/assert/is-same-array' );
 var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var gcusumpw = require( './../lib/ndarray.js' );
 
@@ -213,6 +216,46 @@ tape( 'the function calculates the cumulative sum (accessors)', function test( t
 	t.end();
 });
 
+tape( 'the function preserves the sign of zero', function test( t ) {
+	var expected;
+	var x;
+	var y;
+
+	x = [ -0.0, -0.0, -0.0, 0.0, 1.0 ];
+	y = [ 0.0, 0.0, 0.0, 0.0, 0.0 ];
+
+	gcusumpw( x.length, -0.0, x, 1, 0, y, 1, 0 );
+	expected = [
+		-0.0,
+		-0.0,
+		-0.0,
+		0.0,
+		1.0
+	];
+	t.strictEqual( isSameArray( y, expected ), true, 'returns expected value' );
+	t.end();
+});
+
+tape( 'the function preserves the sign of zero (accessors)', function test( t ) {
+	var expected;
+	var x;
+	var y;
+
+	x = [ -0.0, -0.0, -0.0, 0.0, 1.0 ];
+	y = [ 0.0, 0.0, 0.0, 0.0, 0.0 ];
+
+	gcusumpw( x.length, -0.0, toAccessorArray( x ), 1, 0, toAccessorArray( y ), 1, 0 );
+	expected = [
+		-0.0,
+		-0.0,
+		-0.0,
+		0.0,
+		1.0
+	];
+	t.strictEqual( isSameArray( y, expected ), true, 'returns expected value' );
+	t.end();
+});
+
 tape( 'the function returns a reference to the output array', function test( t ) {
 	var out;
 	var x;