npm package: @stdlib/math-base-special-cflipsign
Description: Return a double-precision complex floating-point number with the same magnitude as `z` and the sign of `y*z`.
Author: The Stdlib Authors
Latest version: 0.2.3

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# cflipsign

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> Return a double-precision complex floating-point number with the same magnitude as `z` and the sign of `y*z`.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-special-cflipsign
```

</section>

<section class="usage">

## Usage

```javascript
var cflipsign = require( '@stdlib/math-base-special-cflipsign' );
```

#### cflipsign( z, y )

Returns a double-precision complex floating-point number with the same magnitude as `z` and the sign of `y*z`.

```javascript
var Complex128 = require( '@stdlib/complex-float64-ctor' );

var v = cflipsign( new Complex128( -4.2, 5.5 ), -1.0 );
// returns <Complex128>[ 4.2, -5.5 ]

```

</section>

<!-- /.usage -->

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<section class="notes">

</section>

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<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var uniform = require( '@stdlib/random-base-uniform' ).factory;
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var cflipsign = require( '@stdlib/math-base-special-cflipsign' );

var rand = uniform( -50.0, 50.0 );

var z;
var y;
var i;
for ( i = 0; i < 100; i++ ) {
    z = new Complex128( rand(), rand() );
    y = rand();
    console.log( 'cflipsign(%s, %d) = %s', z, y, cflipsign( z, y ) );
}
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

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</section>

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<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/math/base/special/cflipsign.h"
```

#### stdlib_base_cflipsign( z, y )

Returns a double-precision complex floating-point number with the same magnitude as `z` and the sign of `y*z`.

```c
#include "stdlib/complex/float64/ctor.h"
#include "stdlib/complex/float64/real.h"
#include "stdlib/complex/float64/imag.h"

stdlib_complex128_t z = stdlib_complex128( 2.5, -1.5 );

stdlib_complex128_t out = stdlib_base_cflipsign( z, -1.0 );

double re = stdlib_complex128_real( out );
// returns -2.5

double im = stdlib_complex128_imag( out );
// returns 1.5
```

The function accepts the following arguments:

-   **z**: `[in] stdlib_complex128_t` input value.
-   **y**: `[in] double` number from which to derive the sign.

```c
stdlib_complex128_t stdlib_base_cflipsign( const stdlib_complex128_t z, const double y );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/math/base/special/cflipsign.h"
#include "stdlib/complex/float64/ctor.h"
#include "stdlib/complex/float64/reim.h"
#include <stdio.h>

int main( void ) {
    const stdlib_complex128_t x[] = {
        stdlib_complex128( 3.14, 1.5 ),
        stdlib_complex128( -3.14, -1.5 ),
        stdlib_complex128( 0.0, 0.0 ),
        stdlib_complex128( 0.0/0.0, 0.0/0.0 )
    };

    stdlib_complex128_t v;
    stdlib_complex128_t y;
    double re1;
    double im1;
    double re2;
    double im2;
    int i;
    for ( i = 0; i < 4; i++ ) {
        v = x[ i ];
        y = stdlib_base_cflipsign( v, -1.0 );
        stdlib_complex128_reim( v, &re1, &im1 );
        stdlib_complex128_reim( y, &re2, &im2 );
        printf( "cflipsign(%lf + %lfi, %lf) = %lf + %lfi\n", re1, im1, -1.0, re2, im2 );
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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</section>

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* * *

## See Also

-   <span class="package-name">[`@stdlib/complex-float64/base/neg`][@stdlib/complex/float64/base/neg]</span><span class="delimiter">: </span><span class="description">negate a double-precision complex floating-point number.</span>
-   <span class="package-name">[`@stdlib/math-base/special/csignum`][@stdlib/math/base/special/csignum]</span><span class="delimiter">: </span><span class="description">evaluate the signum function of a double-precision complex floating-point number.</span>

</section>

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* * *

## 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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[@stdlib/math/base/special/csignum]: https://www.npmjs.com/package/@stdlib/math-base-special-csignum

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