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# fill

> Fill an input [`ndarray`][@stdlib/ndarray/ctor] with a specified value.

<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var fill = require( '@stdlib/ndarray/fill' );
```

#### fill( x, value )

Fills an input [`ndarray`][@stdlib/ndarray/ctor] with a specified value.

```javascript
var zeros = require( '@stdlib/ndarray/zeros' );

var x = zeros( [ 3, 1, 2 ], {
    'dtype': 'float64'
});

var y = fill( x, 10.0 );
// returns <ndarray>[ [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ] ]

var bool = ( y === x );
// returns true
```

The function accepts the following arguments:

-   **x**: array-like object containing an input [`ndarray`][@stdlib/ndarray/ctor].
-   **value**: scalar value.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   An input [`ndarray`][@stdlib/ndarray/ctor] **must** be writable. If provided a **read-only** [`ndarray`][@stdlib/ndarray/ctor], the function throws an error.
-   If `value` is a number and `x` has a complex [data type][@stdlib/ndarray/dtypes], the function fills an input [`ndarray`][@stdlib/ndarray/ctor] with a complex number whose real component equals the provided scalar `value` and whose imaginary component is zero.
-   A `value` must be able to safely cast to the input [`ndarray`][@stdlib/ndarray/ctor] [data type][@stdlib/ndarray/dtypes]. Scalar values having floating-point data types (both real and complex) are allowed to downcast to a lower precision data type of the same kind (e.g., a scalar double-precision floating-point number can be used to fill a `'float32'` input [`ndarray`][@stdlib/ndarray/ctor]).
-   The function **mutates** the input [`ndarray`][@stdlib/ndarray/ctor].

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var zeros = require( '@stdlib/ndarray/zeros' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var fill = require( '@stdlib/ndarray/fill' );

// Create a zero-filled ndarray:
var x = zeros( [ 5, 2 ], {
    'dtype': 'generic'
});
console.log( ndarray2array( x ) );

// Fill the ndarray with a scalar value:
fill( x, 10.0 );
console.log( ndarray2array( x ) );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/ndarray/fill-by`][@stdlib/ndarray/fill-by]</span><span class="delimiter">: </span><span class="description">fill an input ndarray according to a callback function.</span>
-   <span class="package-name">[`@stdlib/ndarray/map`][@stdlib/ndarray/map]</span><span class="delimiter">: </span><span class="description">apply a callback to elements in an input ndarray and assign results to elements in a new output ndarray.</span>
-   <span class="package-name">[`@stdlib/ndarray/zeros`][@stdlib/ndarray/zeros]</span><span class="delimiter">: </span><span class="description">create a zero-filled ndarray having a specified shape and data type.</span>

</section>

<!-- /.related -->

<section class="links">

[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor

[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray/tree/main/dtypes

<!-- <related-links> -->

[@stdlib/ndarray/fill-by]: https://github.com/stdlib-js/ndarray/tree/main/fill-by

[@stdlib/ndarray/map]: https://github.com/stdlib-js/ndarray/tree/main/map

[@stdlib/ndarray/zeros]: https://github.com/stdlib-js/ndarray/tree/main/zeros

<!-- </related-links> -->

</section>

<!-- /.links -->
