@stdlib/array/base/unary4d/README.md

Arrays.

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# unary4d

> Apply a unary callback to elements in a four-dimensional nested input array and assign results to elements in a four-dimensional nested output array.

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<section class="usage">

## Usage

```javascript
var unary4d = require( '@stdlib/array/base/unary4d' );
```

#### unary4d( arrays, shape, fcn )

Applies a unary callback to elements in a four-dimensional nested input array and assigns results to elements in a four-dimensional nested output array.

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

var x = [ [ [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ] ] ];
var shape = [ 1, 1, 2, 2 ];

// Compute the absolute values in-place:
unary4d( [ x, x ], shape, abs );
// x => [ [ [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ] ]
```

The function accepts the following arguments:

-   **arrays**: array-like object containing one input nested array and one output nested array.
-   **shape**: array shape.
-   **fcn**: unary function to apply.

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## Notes

-   The function assumes that the input and output arrays have the same shape.

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<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var filled4dBy = require( '@stdlib/array/base/filled4d-by' );
var zeros4d = require( '@stdlib/array/base/zeros4d' );
var abs = require( '@stdlib/math/base/special/abs' );
var unary4d = require( '@stdlib/array/base/unary4d' );

var shape = [ 2, 2, 3, 3 ];

var x = filled4dBy( shape, discreteUniform( -100, 100 ) );
console.log( x );

var y = zeros4d( shape );
console.log( y );

unary4d( [ x, y ], shape, abs );
console.log( y );
```

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