# fill
> Fill an input [`ndarray`][@stdlib/ndarray/ctor] with a specified value.
## 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 [ [ [ 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.
## 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].
## Examples
```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 ) );
```
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor
[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray/tree/main/dtypes
[@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