# Nullary
> Apply a nullary callback and assign results to elements in a strided output array.
## Usage
```javascript
var nullary = require( '@stdlib/strided/base/nullary' );
```
#### nullary( arrays, shape, strides, fcn )
Applies a nullary callback and assigns results to elements in a strided output array.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
function fill() {
return 3.0;
}
var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
nullary( [ x ], [ x.length ], [ 1 ], fill );
// x => [ 3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0 ]
```
The function accepts the following arguments:
- **arrays**: array-like object containing one strided output array.
- **shape**: array-like object containing a single element, the number of indexed elements.
- **strides**: array-like object containing the stride length for the strided output array.
- **fcn**: nullary function to apply.
The `shape` and `strides` parameters determine which elements in the strided output array are accessed at runtime. For example, to index the first `N` elements of the strided output array in reverse order,
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var floor = require( '@stdlib/math/base/special/floor' );
function fill() {
return 3.0;
}
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var N = floor( x.length / 2 );
nullary( [ x ], [ N ], [ -1 ], fill );
// x => [ 3.0, 3.0, 3.0, -4.0, -5.0, -6.0 ]
```
Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var floor = require( '@stdlib/math/base/special/floor' );
function fill() {
return 3.0;
}
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var N = floor( x0.length / 2 );
nullary( [ x1 ], [ N ], [ 1 ], fill );
// x0 => [ -1.0, 3.0, -3.0, 3.0, -5.0, 3.0 ]
```
#### nullary.ndarray( arrays, shape, strides, offsets, fcn )
Applies a nullary callback and assigns results to elements in a strided output array using alternative indexing semantics.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
function fill() {
return 3.0;
}
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
nullary.ndarray( [ x ], [ x.length ], [ 1 ], [ 0 ], fill );
// x => [ 3.0, 3.0, 3.0, 3.0, 3.0 ]
```
The function accepts the following additional arguments:
- **offsets**: array-like object containing the starting index (i.e., index offset) for the strided output array.
While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the `offsets` parameter supports indexing semantics based on starting indices. For example, to index the last `N` elements in the strided output array,
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var floor = require( '@stdlib/math/base/special/floor' );
function fill() {
return 3.0;
}
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var N = floor( x.length / 2 );
nullary.ndarray( [ x ], [ N ], [ -1 ], [ x.length-1 ], fill );
// x => [ -1.0, -2.0, -3.0, 3.0, 3.0, 3.0 ]
```
## Examples
```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var filledarray = require( '@stdlib/array/filled' );
var nullary = require( '@stdlib/strided/base/nullary' );
var N = 10;
var x = filledarray( 0.0, N, 'generic' );
console.log( x );
var shape = [ N ];
var strides = [ 1 ];
var offsets = [ 0 ];
nullary.ndarray( [ x ], shape, strides, offsets, discreteUniform( -100, 100 ) );
console.log( x );
```
[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray