npm package: @stdlib/ndarray-base-binary-output-dtype
Description: Resolve the output ndarray data type for a binary function.
Author: The Stdlib Authors
Latest version: 0.1.1

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# binaryOutputDataType

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

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### binaryOutputDataType( xdtype, ydtype, policy )

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

```javascript
var dt = binaryOutputDataType( 'int32', 'float32', 'floating_point' );

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

The function supports the following parameters:

-   **xdtype**: first input ndarray [data type][@stdlib/ndarray/dtypes].
-   **ydtype**: second input ndarray [data type][@stdlib/ndarray/dtypes].
-   **policy**: output [data type policy][@stdlib/ndarray/output-dtype-policies].

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

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

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

dt = binaryOutputDataType( 'int32', 'int8', 'float64' );

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

// ...
```

</section>

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<!-- 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 **always** applies [type promotion][@stdlib/ndarray/promotion-rules] to the provided data types, except for the following [data type policies][@stdlib/ndarray/output-dtype-policies]:

    -   `default`
    -   `default_index`
    -   `same`
    -   `<dtype>`

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var naryFunction = require( '@stdlib/utils-nary-function' );
var unzip = require( '@stdlib/utils-unzip' );
var nCartesianProduct = require( '@stdlib/array-base-n-cartesian-product' );
var dtypes = require( '@stdlib/ndarray-dtypes' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var binaryOutputDataType = require( '@stdlib/ndarray-base-binary-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 Cartesian products:
var args = nCartesianProduct( dt, dt, policies );

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

// Resolve output data types:
logEachMap( 'dtypes: (%7s, %7s). policy: %-24s. output dtype: %s.', args[ 0 ], args[ 1 ], args[ 2 ], naryFunction( binaryOutputDataType, 3 ) );
```

</section>

<!-- /.examples -->

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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.

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## License

See [LICENSE][stdlib-license].


## Copyright

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

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