Add utility to cast a function's return value to a complex number

Author: kgryte

lib/node_modules/@stdlib/complex/base/cast-return/README.md

@@ -0,0 +1,136 @@
+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2022 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.
+
+-->
+
+# castReturn
+
+> Wrap a function and cast a function's return value to a complex number.
+
+<!-- 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 castReturn = require( '@stdlib/complex/base/cast-return' );
+```
+
+#### castReturn( fcn, nargs, ctor )
+
+Returns a function which wraps a function and casts a function's return value to a complex number.
+
+```javascript
+var Complex64 = require( '@stdlib/complex/float32' );
+var addf = require( '@stdlib/math/base/ops/addf' );
+
+var f = castReturn( addf, 2, Complex64 );
+// returns <Function>
+```
+
+The function accepts the following arguments:
+
+-   **fcn**: the function to wrap.
+-   **nargs**: the number of arguments to be provided to the wrapped function.
+-   **ctor**: complex number constructor for converting real numbers to complex numbers.
+
+</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 returned function **assumes** that the wrapped function returns either a real or complex number.
+-   The returned function **assumes** that, if a return value is non-numeric (i.e., not of type `number`), then the return value is a complex number. The returned function does **not** verify that non-numeric return values are, in fact, complex number objects. The returned function returns non-numeric return values from the wrapped function without modification.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var Complex64 = require( '@stdlib/complex/float32' );
+var addf = require( '@stdlib/math/base/ops/addf' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+var castReturn = require( '@stdlib/complex/base/cast-return' );
+
+var f = castReturn( addf, 2, Complex64 );
+
+// ...
+
+var z = f( 3.0, 4.0 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns 7.0
+
+var im = imagf( z );
+// returns 0.0
+
+console.log( '%d + %di', re, im );
+// => '7 + 0i'
+```
+
+</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">
+
+</section>
+
+<!-- /.links -->