feat: add ndarray/base/eye

lib/node_modules/@stdlib/ndarray/base/eye/README.md

@@ -0,0 +1,136 @@
+<!--
+
+@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
+
+   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.
+
+-->
+
+# eye
+
+> Create a two-dimensional ndarray with ones on the kth diagonal and zeros elsewhere
+
+<!-- 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 eye = require( '@stdlib/ndarray/base/eye' );
+```
+
+#### eye( dtype, rows, cols, k, order )
+
+Returns a two-dimensional ndarray with ones on the kth diagonal and zeros elsewhere.
+
+```javascript
+var getShape = require( '@stdlib/ndarray/shape' );
+var getDType = require( '@stdlib/ndarray/dtype' );
+
+var arr = eye( 'float64', 3, 3, 0, 'row-major');
+// returns <ndarray>[ [ 1.0, 0.0, 0.0 ], [ 0.0, 1.0, 0.0 ], [ 0.0, 0.0, 1.0 ] ]
+
+var sh = getShape( arr );
+// returns [ 3, 3 ]
+
+var dt = String( getDType( arr ) );
+// returns 'float64'
+```
+
+The function accepts the following arguments:
+
+-   **dtype**: underlying [data type][@stdlib/ndarray/dtypes].
+-   **rows**: number of rows.
+-   **cols**: number of columns.
+-   **k**: diagonal index. positive refers to upper diagonal, and negative refers to lower diagonal.
+-   **order**: specifies whether an [ndarray][@stdlib/ndarray/base/ctor] is `'row-major'` (C-style) or `'column-major'` (Fortran-style).
+
+
+</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
+
+-   If the provided [data type][@stdlib/ndarray/dtypes] is complex, the function returns an ndarray whose kth diagonal is filled with complex numbers whose real component equals one and imaginary component equals zero.
+-   If `k` is greater than the number of columns or less than the number of negative rows, the function returns an ndarray filled with zeros.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var eye = require( '@stdlib/ndarray/base/eye' );
+var ndarray2array = require( '@stdlib/ndarray/to-array' );
+
+var arr = eye( 'float64', 3, 3, 1, 'row-major');
+console.log( ndarray2array( arr ) );
+
+arr = eye( 'complex64', 3, 3, 1, 'row-major');
+console.log( ndarray2array( arr ) );
+```
+
+</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/base/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/base/ctor
+
+[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/dtypes
+
+</section>
+
+<!-- /.links -->