feat: add blas/ext/base/ndarray/gfind-last-index

PR-URL: #7786
Ref: #2656
Co-authored-by: Athan Reines <[email protected]>
Reviewed-by: Athan Reines <[email protected]>

Author: headlessNode

lib/node_modules/@stdlib/blas/ext/base/ndarray/gfind-last-index/README.md

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+<!--
+
+@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.
+
+-->
+
+# gfindLastIndex
+
+> Return the index of the last element in a one-dimensional ndarray which passes a test implemented by a predicate function.
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var gfindLastIndex = require( '@stdlib/blas/ext/base/ndarray/gfind-last-index' );
+```
+
+#### gfindLastIndex( arrays, clbk\[, thisArg] )
+
+Returns the index of the last element in a one-dimensional ndarray which passes a test implemented by a predicate function.
+
+```javascript
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+
+function isEven( v ) {
+    return v % 2.0 === 0.0;
+}
+
+var xbuf = [ 1.0, 3.0, 4.0, 2.0 ];
+var x = new ndarray( 'generic', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
+
+var idx = gfindLastIndex( [ x ], isEven );
+// returns 3
+```
+
+If no element passes a test implemented by a predicate function, the function returns `-1`.
+
+```javascript
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+
+function isEven( v ) {
+    return v % 2.0 === 0.0;
+}
+
+var xbuf = [ 1.0, 3.0, 5.0, 7.0 ];
+var x = new ndarray( 'generic', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
+
+var idx = gfindLastIndex( [ x ], isEven );
+// returns -1
+```
+
+The function has the following parameters:
+
+-   **arrays**: array-like object containing a one-dimensional input ndarray.
+-   **clbk**: callback function.
+-   **thisArg**: callback execution context (_optional_).
+
+The callback function is provided the following arguments:
+
+-   **value**: current array element.
+-   **idx**: current array element index.
+-   **array**: the input ndarray.
+
+To set the callback execution context, provide a `thisArg`.
+
+```javascript
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+
+function isEven( v ) {
+    this.count += 1;
+    return v % 2.0 === 0.0;
+}
+
+var xbuf = [ 1.0, 3.0, 4.0, 2.0 ];
+var x = new ndarray( 'generic', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
+var ctx = {
+    'count': 0
+};
+
+var v = gfindLastIndex( [ x ], isEven, ctx );
+// returns 3
+
+var count = ctx.count;
+// returns 1
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If provided an empty one-dimensional ndarray, the function returns `-1`.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+var ndarray2array = require( '@stdlib/ndarray/to-array' );
+var gfindLastIndex = require( '@stdlib/blas/ext/base/ndarray/gfind-last-index' );
+
+function isEven( v ) {
+    return v % 2.0 === 0.0;
+}
+
+var xbuf = discreteUniform( 10, -100, 100, {
+    'dtype': 'generic'
+});
+var x = new ndarray( 'generic', xbuf, [ xbuf.length ], [ 1 ], 0, 'row-major' );
+console.log( ndarray2array( x ) );
+
+var idx = gfindLastIndex( [ x ], isEven );
+console.log( idx );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/ext/base/ndarray/gfind-last-index/benchmark/benchmark.js

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+/**
+* @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 bench = require( '@stdlib/bench' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+var pkg = require( './../package.json' ).name;
+var gfindLastIndex = require( './../lib' );
+
+
+// VARIABLES //
+
+var options = {
+	'dtype': 'generic'
+};
+
+
+// FUNCTIONS //
+
+/**
+* Callback function.
+*
+* @private
+* @param {number} v - array element
+* @returns {boolean} result
+*/
+function clbk( v ) {
+	return v < 0.0;
+}
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var xbuf;
+	var x;
+
+	xbuf = uniform( len, 0.0, 100.0, options );
+	x = new ndarray( options.dtype, xbuf, [ len ], [ 1 ], 0, 'row-major' );
+
+	return benchmark;
+
+	function benchmark( b ) {
+		var v;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			v = gfindLastIndex( [ x ], clbk );
+			if ( isnan( v ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnan( v ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var len;
+	var min;
+	var max;
+	var f;
+	var i;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		len = pow( 10, i );
+		f = createBenchmark( len );
+		bench( pkg+':len='+len, f );
+	}
+}
+
+main();

lib/node_modules/@stdlib/blas/ext/base/ndarray/gfind-last-index/docs/repl.txt

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+
+{{alias}}( arrays, clbk[, thisArg] )
+    Returns the index of the last element in a one-dimensional ndarray which
+    passes a test implemented by a predicate function.
+
+    If provided an empty ndarray or no element passes a test implemented by a
+    predicate function, the function returns `-1`.
+
+    The callback function is provided three arguments:
+
+    - value: current array element.
+    - index: current array index.
+    - array: the input ndarray.
+
+    Parameters
+    ----------
+    arrays: ArrayLikeObject<ndarray>
+        Array-like object containing a one-dimensional input ndarray.
+
+    clbk: Function
+        Callback function.
+
+    thisArg: any (optional)
+        Callback execution context.
+
+    Returns
+    -------
+    out: integer
+        Index.
+
+    Examples
+    --------
+    > var xbuf = [ 1.0, -2.0, 2.0 ];
+    > var dt = 'generic';
+    > var sh = [ xbuf.length ];
+    > var sx = [ 1 ];
+    > var ox = 0;
+    > var ord = 'row-major';
+    > var x = new {{alias:@stdlib/ndarray/ctor}}( dt, xbuf, sh, sx, ox, ord );
+    > function f ( v ) { return v % 2.0 === 0.0; };
+    > {{alias}}( [ x ], f )
+    2
+
+    See Also
+    --------