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

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# ternaryOutputDataType

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

<!-- 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>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### ternaryOutputDataType( xdtype, ydtype, zdtype, policy )

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

```javascript
var dt = ternaryOutputDataType( 'int32', 'float32', '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].
-   **zdtype**: third 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 = ternaryOutputDataType( 'float32', 'float32', 'float32', 'float64' );

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

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

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

// ...
```

</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 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 ternaryOutputDataType = require( '@stdlib/ndarray-base-ternary-output-dtype' );

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

// 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, dt, policies );

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

// Resolve output data types:
logEachMap( 'dtypes: (%7s, %7s, %7s). policy: %-24s. output dtype: %s.', args[ 0 ], args[ 1 ], args[ 2 ], args[ 3 ], naryFunction( ternaryOutputDataType, 4 ) );
```

</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.

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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