npm package: @stdlib/math-array-tools-unary
Description: Constructor for applying a unary function to each element in an input array.
Author: The Stdlib Authors
Latest version: 0.1.1

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# Unary

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> Constructor for applying a unary function to each element in an input array.

<section class="installation">

## Installation

```bash
npm install @stdlib/math-array-tools-unary
```

</section>

<section class="usage">

## Usage

```javascript
var Unary = require( '@stdlib/math-array-tools-unary' );
```

#### Unary( fcn, idtypes, odtypes, policy )

Constructor for applying a unary function to each element in an input array.

```javascript
var abs = require( '@stdlib/math-base-special-abs' );

var dtypes = [ 'float64', 'float32', 'generic' ];
var policy = 'same';

var unary = new Unary( abs, dtypes, dtypes, policy );
```

The constructor has the following parameters:

-   **fcn**: unary function to apply.
-   **idtypes**: list of supported input data types.
-   **odtypes**: list of supported input data types.
-   **policy**: output data type policy.

#### Unary.prototype.apply( x\[, options] )

Applies a unary function to each element in a provided input array.

```javascript
var abs = require( '@stdlib/math-base-special-abs' );

var dtypes = [ 'float64', 'float32', 'generic' ];
var policy = 'same';

var unary = new Unary( abs, dtypes, dtypes, policy );

var v = unary.apply( [ -1.0, 2.0, -3.0, 4.0 ] );
// returns [ 1.0, 2.0, 3.0, 4.0 ]
```

The method has the following parameters:

-   **x**: input array.
-   **options**: function options.

The method accepts the following options:

-   **dtype**: output array data type. Setting this option, overrides the output data type policy.

By default, the method returns an array having a data type determined by the output data type policy. To override the default behavior, set the `dtype` option.

```javascript
var abs = require( '@stdlib/math-base-special-abs' );

var dtypes = [ 'float64', 'float32', 'generic' ];
var policy = 'same';

var unary = new Unary( abs, dtypes, dtypes, policy );

var v = unary.apply( [ -1.0, 2.0, -3.0, 4.0 ], {
    'dtype': 'float64'
});
// returns <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
```

#### Unary.prototype.assign( x, out )

Applies a unary function to each element in a provided input array and assigns results to a provided output array.

```javascript
var abs = require( '@stdlib/math-base-special-abs' );
var zeros = require( '@stdlib/array-zeros' );

var dtypes = [ 'float64', 'float32', 'generic' ];
var policy = 'same';

var unary = new Unary( abs, dtypes, dtypes, policy );

var out = zeros( 4, 'float64' );
// returns <Float64Array>[ 0.0, 0.0, 0.0, 0.0 ]

var v = unary.assign( [ -1.0, 2.0, -3.0, 4.0 ], out );
// returns <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]

var bool = ( v === out );
// returns true
```

The method has the following parameters:

-   **x**: input array.
-   **out**: output array.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   The output data type policy only applies to the `apply` method. For the `assign` method, the output array is allowed to be any array-like object, including [accessor arrays][@stdlib/array/base/accessor].

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var base = require( '@stdlib/math-base-special-sin' );
var uniform = require( '@stdlib/random-array-uniform' );
var dtypes = require( '@stdlib/array-dtypes' );
var dtype = require( '@stdlib/array-dtype' );
var logEach = require( '@stdlib/console-log-each' );
var Unary = require( '@stdlib/math-array-tools-unary' );

// Define the supported input and output data types:
var idt = dtypes( 'real_and_generic' );
var odt = dtypes( 'real_floating_point_and_generic' );

// Define the policy mapping an input data type to an output data type:
var policy = 'real_floating_point_and_generic';

// Create an interface for computing the element-wise sine:
var sin = new Unary( base, idt, odt, policy );

// Generate an array of random numbers:
var x = uniform( 10, -1.0, 1.0, {
    'dtype': 'generic'
});

// Compute the element-wise sine:
var y = sin.apply( x );

// Resolve the output array data type:
var dt = dtype( y );
console.log( dt );

// Print the results:
logEach( 'sin(%0.5f) = %0.5f', x, y );
```

</section>

<!-- /.examples -->

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<section class="related">

</section>

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<section class="main-repo" >

* * *

## 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].

#### Community

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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[@stdlib/array/base/accessor]: https://www.npmjs.com/package/@stdlib/array-base-accessor

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