feat: add ndarray/concat

lib/node_modules/@stdlib/ndarray/concat/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.
+
+-->
+
+# concat
+
+> Concatenate a list of [ndarrays][@stdlib/ndarray/ctor] along a specified [ndarray][@stdlib/ndarray/ctor] dimension.
+
+<!-- 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
+
+```javascript
+var concat = require( '@stdlib/ndarray/concat' );
+```
+
+#### concat( arrays\[, dim] )
+
+Concatenates a list of [ndarrays][@stdlib/ndarray/ctor] along a specified [ndarray][@stdlib/ndarray/ctor] dimension.
+
+```javascript
+var array = require( '@stdlib/ndarray/array' );
+var ndarray2array = require( '@stdlib/ndarray/to-array' );
+
+var x = array( [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ] );
+var y = array( [ [ -5.0, 6.0, -7.0 ], [ 8.0, -9.0, 10.0 ] ] );
+
+var out = concat( [ x, y ], -1 );
+// returns <ndarray>
+
+var arr = ndarray2array( out );
+// returns [ [ -1.0, 2.0, -5.0, 6.0, -7.0 ], [ -3.0, 4.0, 8.0, -9.0, 10.0 ] ]
+```
+
+The function accepts the following arguments:
+
+-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. Must be [broadcast compatible][@stdlib/ndarray/base/broadcast-shapes] except for the dimension along which to concatenate. The data type of the output [ndarray][@stdlib/ndarray/ctor] is determined by applying [type promotion rules][@stdlib/ndarray/promotion-rules] to the list of input [ndarrays][@stdlib/ndarray/ctor]. If provided [ndarrays][@stdlib/ndarray/ctor] having different [memory layouts][@stdlib/ndarray/orders], the output [ndarray][@stdlib/ndarray/ctor] has the [default order][@stdlib/ndarray/defaults].
+-   **dim**: dimension along which to concatenate input [ndarrays][@stdlib/ndarray/ctor] (_optional_). Must be a negative integer. The index of the dimension along which to concatenate is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. Default: `-1`.
+
+#### concat.assign( arrays, out\[, dim] )
+
+Concatenates a list of ndarrays along a specified ndarray dimension and assigns results to an output ndarray.
+
+```javascript
+var array = require( '@stdlib/ndarray/array' );
+var zeros = require( '@stdlib/ndarray/zeros' );
+var ndarray2array = require( '@stdlib/ndarray/to-array' );
+
+var x = array( [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ] );
+var y = array( [ [ -5.0, 6.0, -7.0 ], [ 8.0, -9.0, 10.0 ] ] );
+
+var z = zeros( [ 2, 5 ] );
+
+var out = concat.assign( [ x, y ], z, -1 );
+// returns <ndarray>
+
+var bool = ( out === z );
+// returns true
+
+var arr = ndarray2array( z );
+// returns [ [ -1.0, 2.0, -5.0, 6.0, -7.0 ], [ -3.0, 4.0, 8.0, -9.0, 10.0 ] ]
+```
+
+The function accepts the following arguments:
+
+-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. Must be [broadcast compatible][@stdlib/ndarray/base/broadcast-shapes] except for the dimension along which to concatenate. Must [promote][@stdlib/ndarray/promotion-rules] to a [data type][@stdlib/ndarray/dtypes] which can be (mostly) [safely cast][@stdlib/ndarray/mostly-safe-casts] to the [data type][@stdlib/ndarray/dtypes] of the output [ndarray][@stdlib/ndarray/ctor].
+-   **out**: output [ndarray][@stdlib/ndarray/ctor].
+-   **dim**: dimension along which to concatenate input [ndarrays][@stdlib/ndarray/ctor] (_optional_). Must be a negative integer. The index of the dimension along which to concatenate is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. Default: `-1`.
+
+</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">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+```javascript
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
+var ndarray = require( '@stdlib/ndarray/ctor' );
+var ndarray2array = require( '@stdlib/ndarray/to-array' );
+var concat = require( '@stdlib/ndarray/concat' );
+
+var xbuf = discreteUniform( 6, 0, 10, {
+    'dtype': 'generic'
+});
+var x = new ndarray( 'generic', xbuf, [ 2, 3 ], [ 3, 1 ], 0, 'row-major' );
+console.log( ndarray2array( x ) );
+
+var ybuf = discreteUniform( 8, 0, 10, {
+    'dtype': 'generic'
+});
+var y = new ndarray( 'generic', ybuf, [ 2, 4 ], [ 4, 1 ], 0, 'row-major' );
+console.log( ndarray2array( y ) );
+
+var out = concat( [ x, y ], -1 );
+console.log( ndarray2array( out ) );
+```
+
+</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/dtypes]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/dtypes
+
+[@stdlib/ndarray/orders]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/orders
+
+[@stdlib/ndarray/defaults]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/defaults
+
+[@stdlib/ndarray/promotion-rules]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/promotion-rules
+
+[@stdlib/ndarray/mostly-safe-casts]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/mostly-safe-casts
+
+[@stdlib/ndarray/base/broadcast-shapes]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/base/broadcast-shapes
+
+</section>
+
+<!-- /.links -->