fix: update fromIndex handling in blas/ext/base/ndarray/slast-index-of

PR-URL: stdlib-js#8007
Closes: stdlib-js/metr-issue-tracker#71
Ref: stdlib-js#2656
Reviewed-by: Athan Reines <[email protected]>

Author: headlessNode

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/README.md

@@ -52,7 +52,7 @@ var searchElement = scalar2ndarray( 2.0, {
     'dtype': 'float32'
 });
 
-var fromIndex = scalar2ndarray( 0, {
+var fromIndex = scalar2ndarray( 3, {
     'dtype': 'generic'
 });
 
@@ -82,7 +82,7 @@ var searchElement = scalar2ndarray( 10.0, {
     'dtype': 'float32'
 });
 
-var fromIndex = scalar2ndarray( 0, {
+var fromIndex = scalar2ndarray( 3, {
     'dtype': 'generic'
 });
 
@@ -129,7 +129,7 @@ var searchElement = scalar2ndarray( 80.0, {
 });
 console.log( 'Search Element:', ndarraylike2scalar( searchElement ) );
 
-var fromIndex = scalar2ndarray( 0, {
+var fromIndex = scalar2ndarray( -1, {
     'dtype': 'generic'
 });
 console.log( 'From Index:', ndarraylike2scalar( fromIndex ) );

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/benchmark/benchmark.js

@@ -58,7 +58,7 @@ function createBenchmark( len ) {
 	searchElement = scalar2ndarray( -10.0, {
 		'dtype': 'float32'
 	});
-	fromIndex = scalar2ndarray( 0, {
+	fromIndex = scalar2ndarray( -1, {
 		'dtype': 'generic'
 	});
 

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/docs/types/index.d.ts

@@ -34,14 +34,14 @@ import { float32ndarray, typedndarray } from '@stdlib/types/ndarray';
 * var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
 * var slastIndexOf = require( '@stdlib/blas/ext/base/ndarray/slast-index-of' );
 *
-* var xbuf = new Float32Array( [ 1.0, 3.0, 4.0, 2.0 ] );
+* var xbuf = new Float32Array( [ 1.0, 2.0, 4.0, 2.0 ] );
 * var x = new ndarray( 'float32', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
 *
 * var searchElement = scalar2ndarray( 2.0, {
 *     'dtype': 'float32'
 * });
 *
-* var fromIndex = scalar2ndarray( 0, {
+* var fromIndex = scalar2ndarray( 3, {
 *     'dtype': 'generic'
 * });
 *

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/examples/index.js

@@ -36,7 +36,7 @@ var searchElement = scalar2ndarray( 80.0, {
 });
 console.log( 'Search Element:', ndarraylike2scalar( searchElement ) );
 
-var fromIndex = scalar2ndarray( 0, {
+var fromIndex = scalar2ndarray( -1, {
 	'dtype': 'generic'
 });
 console.log( 'From Index:', ndarraylike2scalar( fromIndex ) );

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/lib/index.js

@@ -29,14 +29,14 @@
 * var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
 * var slastIndexOf = require( '@stdlib/blas/ext/base/ndarray/slast-index-of' );
 *
-* var xbuf = new Float32Array( [ 1.0, 3.0, 4.0, 2.0 ] );
+* var xbuf = new Float32Array( [ 1.0, 2.0, 4.0, 2.0 ] );
 * var x = new ndarray( 'float32', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
 *
 * var searchElement = scalar2ndarray( 2.0, {
 *     'dtype': 'float32'
 * });
 *
-* var fromIndex = scalar2ndarray( 0, {
+* var fromIndex = scalar2ndarray( 3, {
 *     'dtype': 'generic'
 * });
 *

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/lib/main.js

@@ -41,14 +41,14 @@ var ndarraylike2scalar = require( '@stdlib/ndarray/base/ndarraylike2scalar' );
 * var ndarray = require( '@stdlib/ndarray/base/ctor' );
 * var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
 *
-* var xbuf = new Float32Array( [ 1.0, 3.0, 4.0, 2.0 ] );
+* var xbuf = new Float32Array( [ 1.0, 2.0, 4.0, 2.0 ] );
 * var x = new ndarray( 'float32', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
 *
 * var searchElement = scalar2ndarray( 2.0, {
 *     'dtype': 'float32'
 * });
 *
-* var fromIndex = scalar2ndarray( 0, {
+* var fromIndex = scalar2ndarray( 3, {
 *     'dtype': 'generic'
 * });
 *
@@ -58,9 +58,6 @@ var ndarraylike2scalar = require( '@stdlib/ndarray/base/ndarraylike2scalar' );
 function slastIndexOf( arrays ) {
 	var searchElement;
 	var fromIndex;
-	var stride;
-	var offset;
-	var idx;
 	var N;
 	var x;
 
@@ -72,20 +69,12 @@ function slastIndexOf( arrays ) {
 	if ( fromIndex < 0 ) {
 		fromIndex += N;
 		if ( fromIndex < 0 ) {
-			fromIndex = 0;
+			return -1;
 		}
 	} else if ( fromIndex >= N ) {
-		return -1;
+		fromIndex = N - 1;
 	}
-	N -= fromIndex;
-	stride = getStride( x, 0 );
-	offset = getOffset( x ) + ( stride*fromIndex );
-
-	idx = strided( N, searchElement, getData( x ), stride, offset );
-	if ( idx >= 0 ) {
-		idx += fromIndex;
-	}
-	return idx;
+	return strided( fromIndex+1, searchElement, getData( x ), getStride( x, 0 ), getOffset( x ) ); // eslint-disable-line max-len
 }
 
 

lib/node_modules/@stdlib/blas/ext/base/ndarray/slast-index-of/test/test.js

@@ -64,7 +64,7 @@ tape( 'the function returns the last index of an element which equals a provided
 	searchElement = scalar2ndarray( 1.0, {
 		'dtype': 'float32'
 	});
-	fromIndex = scalar2ndarray( 0, {
+	fromIndex = scalar2ndarray( 5, {
 		'dtype': 'generic'
 	});
 	actual = slastIndexOf( [ x, searchElement, fromIndex ] );
@@ -73,7 +73,7 @@ tape( 'the function returns the last index of an element which equals a provided
 	searchElement = scalar2ndarray( 2.0, {
 		'dtype': 'float32'
 	});
-	fromIndex = scalar2ndarray( 0, {
+	fromIndex = scalar2ndarray( 5, {
 		'dtype': 'generic'
 	});
 	actual = slastIndexOf( [ x, searchElement, fromIndex ] );
@@ -114,7 +114,7 @@ tape( 'the function returns the last index of an element which equals a provided
 		'dtype': 'generic'
 	});
 	actual = slastIndexOf( [ x, searchElement, fromIndex ] );
-	t.strictEqual( actual, 5, 'returns expected value' );
+	t.strictEqual( actual, 4, 'returns expected value' );
 
 	searchElement = scalar2ndarray( 2.0, {
 		'dtype': 'float32'
@@ -132,12 +132,12 @@ tape( 'the function returns the last index of an element which equals a provided
 		'dtype': 'generic'
 	});
 	actual = slastIndexOf( [ x, searchElement, fromIndex ] );
-	t.strictEqual( actual, 3, 'returns expected value' );
+	t.strictEqual( actual, -1, 'returns expected value' );
 
 	t.end();
 });
 
-tape( 'the function returns `-1` if provided a starting search index which is greater than or equal to number of elements in the input ndarray', function test( t ) {
+tape( 'the function clamps the provided starting search index if it is greater than or equal to number of elements in the input ndarray', function test( t ) {
 	var searchElement;
 	var fromIndex;
 	var actual;
@@ -152,7 +152,7 @@ tape( 'the function returns `-1` if provided a starting search index which is gr
 	});
 
 	actual = slastIndexOf( [ x, searchElement, fromIndex ] );
-	t.strictEqual( actual, -1, 'returns expected value' );
+	t.strictEqual( actual, 3, 'returns expected value' );
 
 	t.end();
 });