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# greplicate

> Replicate each strided array element a specified number of times.

<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var greplicate = require( '@stdlib/blas/ext/base/greplicate' );
```

#### greplicate( N, k, x, strideX, out, strideOut )

Replicates each strided array element a specified number of times.

```javascript
var x = [ 1.0, 2.0, 3.0 ];
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

greplicate( x.length, 2, x, 1, out, 1 );
// out => [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ]
```

The function has the following parameters:

-   **N**: number of indexed elements.
-   **k**: number of times to replicate each element.
-   **x**: input array.
-   **strideX**: stride length for `x`.
-   **out**: output array.
-   **strideOut**: stride length for `out`.

The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to replicate every other element:

```javascript
var x = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

greplicate( 3, 2, x, 2, out, 1 );
// out => [ 1.0, 1.0, 3.0, 3.0, 5.0, 5.0 ]
```

Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.

<!-- eslint-disable stdlib/capitalized-comments -->

```javascript
var Float64Array = require( '@stdlib/array/float64' );

// Initial arrays...
var x0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var out0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var out1 = new Float64Array( out0.buffer, out0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

greplicate( 3, 2, x1, 2, out1, 1 );
// out0 => <Float64Array>[ 0.0, 0.0, 2.0, 2.0, 4.0, 4.0, 6.0, 6.0 ]
```

#### greplicate.ndarray( N, k, x, strideX, offsetX, out, strideOut, offsetOut )

Replicates each strided array element a specified number of times using alternative indexing semantics.

```javascript
var x = [ 1.0, 2.0, 3.0 ];
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

greplicate.ndarray( x.length, 2, x, 1, 0, out, 1, 0 );
// out => [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ]
```

The function has the following additional parameters:

-   **offsetX**: starting index for `x`.
-   **offsetOut**: starting index for `out`.

While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, offset parameters support indexing semantics based on starting indices. For example, to replicate every other element in the strided input array starting from the second element and to store in the last `N*k` elements of the strided output array starting from the last element:

```javascript
var x = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

greplicate.ndarray( 3, 2, x, 2, 1, out, -1, out.length-1 );
// out => [ 0.0, 0.0, 6.0, 6.0, 4.0, 4.0, 2.0, 2.0 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If `N <= 0` or `k <= 0`, both functions return `out` unchanged.
-   Both functions assume that the output array supports `N*k` indexed elements.
-   Both functions support array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array/base/accessor`][@stdlib/array/base/accessor]).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var Float64Array = require( '@stdlib/array/float64' );
var greplicate = require( '@stdlib/blas/ext/base/greplicate' );

var x = discreteUniform( 10, -100, 100, {
    'dtype': 'float64'
});
console.log( x );

var out = new Float64Array( x.length * 3 );
console.log( out );

greplicate( x.length, 3, x, 1, out, 1 );
console.log( out );
```

</section>

<!-- /.examples -->

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

<section class="related">

</section>

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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray

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

</section>

<!-- /.links -->
