npm package: @stdlib/ndarray-base-unary-output-dtype
Description: Resolve the output ndarray data type for a unary function.
Author: The Stdlib Authors
Latest version: 0.3.1

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# unaryOutputDataType

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Resolve the output ndarray [data type][@stdlib/ndarray/dtypes] for a unary function.

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</section>

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<section class="installation">

## Installation

```bash
npm install @stdlib/ndarray-base-unary-output-dtype
```

</section>

<section class="usage">

## Usage

```javascript
var unaryOutputDataType = require( '@stdlib/ndarray-base-unary-output-dtype' );
```

#### unaryOutputDataType( dtype, policy )

Resolves the output ndarray [data type][@stdlib/ndarray/dtypes] for a unary function according to a [data type policy][@stdlib/ndarray/output-dtype-policies].

```javascript
var dt = unaryOutputDataType( 'int32', 'floating_point' );

var s = String( dt );
// returns 'float64'
```

If `policy` is a [data type][@stdlib/ndarray/dtypes], the function always returns the `policy` value (i.e., the second argument).

```javascript
var dt = unaryOutputDataType( 'float32', 'float64' );

var s = String( dt );
// returns 'float64'

dt = unaryOutputDataType( 'int32', 'float64' );

s = String( dt );
// returns 'float64'

// ...
```

</section>

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<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var naryFunction = require( '@stdlib/utils-nary-function' );
var map2 = require( '@stdlib/utils-map2' );
var unzip = require( '@stdlib/utils-unzip' );
var cartesianProduct = require( '@stdlib/array-base-cartesian-product' );
var dtypes = require( '@stdlib/ndarray-dtypes' );
var logEach = require( '@stdlib/console-log-each' );
var unaryOutputDataType = require( '@stdlib/ndarray-base-unary-output-dtype' );

// Get the list of real-valued data types:
var dt = dtypes( 'real' );

// Define a list of output data type policies:
var policies = [
    'default',
    'real',
    'floating_point',
    'complex_floating_point'
];

// Generate dtype-policy argument pairs:
var args = cartesianProduct( dt, policies );

// Unzip the argument pair array:
args = unzip( args );

// Resolve output data types:
var out = map2( args[ 0 ], args[ 1 ], naryFunction( unaryOutputDataType, 2 ) );

// Print results:
logEach( 'dtypes: (%10s, %10s). policy: %s.', args[ 0 ], out, args[ 1 ] );
```

</section>

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* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[@stdlib/ndarray/dtypes]: https://www.npmjs.com/package/@stdlib/ndarray-dtypes

[@stdlib/ndarray/output-dtype-policies]: https://www.npmjs.com/package/@stdlib/ndarray-output-dtype-policies

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