npm package: @stdlib/lapack-base-zlacgv
Description: Conjugate each element in a double-precision complex floating-point vector.
Author: The Stdlib Authors
Latest version: 0.1.1

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# zlacgv

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> Conjugate each element in a double-precision complex floating-point vector.

<section class="installation">

## Installation

```bash
npm install @stdlib/lapack-base-zlacgv
```

</section>

<section class="usage">

## Usage

```javascript
var zlacgv = require( '@stdlib/lapack-base-zlacgv' );
```

#### zlacgv( N, zx, strideZX )

Conjugates each element in a double-precision complex floating-point vector.

```javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0 ] );

zlacgv( 2, zx, 1 );

var z = zx.get( 0 );
// returns <Complex128>[ 1.0, -2.0 ]
```

The function has the following parameters:

-   **N**: number of indexed elements.
-   **zx**: input [`Complex128Array`][@stdlib/array/complex128].
-   **strideZX**: stride length for `zx`.

The `N` and stride parameters determine which elements in `zx` are conjugated. For example, to conjugate every other element in `zx`,

```javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

zlacgv( 2, zx, 2 );

var z = zx.get( 0 );
// returns <Complex128>[ 1.0, -2.0 ]
```

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 Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );

// Initial array:
var zx0 = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

// Create an offset view:
var zx1 = new Complex128Array( zx0.buffer, zx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Conjugate every element in `zx1`:
zlacgv( 3, zx1, 1 );

var z = zx0.get( 1 );
// returns <Complex128>[ 3.0, -4.0 ]
```

#### zlacgv.ndarray( N, zx, strideZX, offsetZX )

Conjugates each element in a double-precision floating-point vector using alternative indexing semantics.

```javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

zlacgv.ndarray( 3, zx, 1, 0 );

var z = zx.get( 0 );
// returns <Complex128>[ 1.0, -2.0 ]
```

The function has the following additional parameters:

-   **offsetZX**: starting index for `zx`.

While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to conjugate every other element in the input strided array starting from the second element,

```javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

zlacgv.ndarray( 2, zx, 2, 1 );

var z = zx.get( 3 );
// returns <Complex128>[ 7.0, -8.0 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If `N <= 0`, both functions return `zx` unchanged.
-   `zlacgv()` corresponds to the [LAPACK][lapack] BLAS-like level 1 routine [`zlacgv`][zlacgv].

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var zlacgv = require( '@stdlib/lapack-base-zlacgv' );

function rand() {
    return new Complex128( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
}

var zx = filledarrayBy( 10, 'complex128', rand );
console.log( zx.toString() );

// Conjugate elements:
zlacgv( zx.length, zx, 1 );
console.log( zx.get( zx.length-1 ).toString() );
```

</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 class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[lapack]: https://www.netlib.org/lapack

[zlacgv]: https://www.netlib.org/lapack/explore-html/d9/d50/group__lacgv_gae42087fcabd33130fcbac2aff031de8b.html#gae42087fcabd33130fcbac2aff031de8b

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

[@stdlib/array/complex128]: https://www.npmjs.com/package/@stdlib/array-complex128

</section>

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