feat: add ndarray/base/maybe-broadcast-array-except-dimensions

PR-URL: #10413
Closes: stdlib-js/metr-issue-tracker#167
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: headlessNode

lib/node_modules/@stdlib/ndarray/base/maybe-broadcast-array-except-dimensions/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 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
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+   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.
+
+-->
+
+# maybeBroadcastArrayExceptDimensions
+
+> Broadcast an [ndarray][@stdlib/ndarray/base/ctor] to a specified shape while keeping a list of specified dimensions unchanged if and only if the specified shape differs from the provided [ndarray][@stdlib/ndarray/base/ctor]'s shape.
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+<!-- eslint-disable id-length -->
+
+```javascript
+var maybeBroadcastArrayExceptDimensions = require( '@stdlib/ndarray/base/maybe-broadcast-array-except-dimensions' );
+```
+
+#### maybeBroadcastArrayExceptDimensions( arr, shape, dims )
+
+Broadcasts an [ndarray][@stdlib/ndarray/base/ctor] to a specified shape while keeping a list of specified dimensions unchanged if and only if the specified shape differs from the provided [ndarray][@stdlib/ndarray/base/ctor]'s shape.
+
+<!-- eslint-disable id-length -->
+
+```javascript
+var array = require( '@stdlib/ndarray/array' );
+
+// Create a 2x2 ndarray:
+var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
+// returns <ndarray>[ [ 1, 2 ], [ 3, 4 ] ]
+
+// Perform broadcasting:
+var y = maybeBroadcastArrayExceptDimensions( x, [ 3, 2, 2 ], [ -1 ] );
+// returns <ndarray>[ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 1, 2 ], [ 3, 4 ] ], [ [ 1, 2 ], [ 3, 4 ] ] ]
+```
+
+The function accepts the following arguments:
+
+-   **arr**: input [ndarray][@stdlib/ndarray/base/ctor].
+-   **shape**: target shape.
+-   **dims**: list of dimensions to exclude from broadcasting. Should be a list of negative integers.
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+## Notes
+
+-   The function throws an error if a provided [ndarray][@stdlib/ndarray/base/ctor] is [incompatible][@stdlib/ndarray/base/broadcast-shapes] with a provided shape.
+-   If a provided [ndarray][@stdlib/ndarray/base/ctor] has the same shape as the specified shape (excluding the list of specified dimensions), the function returns the provided [ndarray][@stdlib/ndarray/base/ctor].
+-   If a provided [ndarray][@stdlib/ndarray/base/ctor] has a different (broadcast compatible) shape than the specified shape, the function returns a new (base) [ndarray][@stdlib/ndarray/base/ctor] view of the provided [ndarray][@stdlib/ndarray/base/ctor]'s data. The view is typically **not** contiguous. As more than one element of a returned view may refer to the same memory location, writing to the view may affect multiple elements. If you need to write to the returned [ndarray][@stdlib/ndarray/base/ctor], copy the [ndarray][@stdlib/ndarray/base/ctor] **before** performing operations which may mutate elements.
+-   If a provided [ndarray][@stdlib/ndarray/base/ctor] does not have the same shape as the specified shape (excluding the list of specified dimensions), the returned [ndarray][@stdlib/ndarray/base/ctor] is a "base" [ndarray][@stdlib/ndarray/base/ctor], and, thus, the returned [ndarray][@stdlib/ndarray/base/ctor] does not perform bounds checking or afford any of the guarantees of the non-base [ndarray][@stdlib/ndarray/ctor] constructor. The primary intent of this function is to broadcast an ndarray-like object within internal implementations and to do so with minimal overhead.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint-disable id-length -->
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var array = require( '@stdlib/ndarray/array' );
+var numel = require( '@stdlib/ndarray/base/numel' );
+var ind2sub = require( '@stdlib/ndarray/ind2sub' );
+var getShape = require( '@stdlib/ndarray/shape' );
+var maybeBroadcastArrayExceptDimensions = require( '@stdlib/ndarray/base/maybe-broadcast-array-except-dimensions' );
+
+// Create a 1x3 array:
+var x = array( [ [ 1, 2, 3 ] ] );
+// returns <ndarray>[ [ 1, 2, 3 ] ]
+
+// Broadcast the array to 2x1x3:
+var y = maybeBroadcastArrayExceptDimensions( x, [ 2, 2, 3 ], [ -2 ] );
+// returns <ndarray>[ [ [ 1, 2, 3 ] ], [ [ 1, 2, 3 ] ] ]
+
+// Retrieve the shape:
+var sh = getShape( y );
+// returns [ 2, 1, 3 ]
+
+// Retrieve the number of elements:
+var N = numel( sh );
+
+// Loop through the array elements...
+var sub;
+var v;
+var i;
+for ( i = 0; i < N; i++ ) {
+    v = y.iget( i );
+    sub = ind2sub( sh, i );
+    console.log( 'Y[%s] = %d', sub.join( ', ' ), v );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- 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">
+
+[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/ctor
+
+[@stdlib/ndarray/base/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/base/ctor
+
+[@stdlib/ndarray/base/broadcast-shapes]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/base/broadcast-shapes
+
+</section>
+
+<!-- /.links -->