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# cpolar

> Compute the [absolute value][@stdlib/math/base/special/cabs] and [phase][@stdlib/math/base/special/cphase] of a double-precision complex floating-point number.

<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

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

#### cpolar( z )

Computes the [absolute value][@stdlib/math/base/special/cabs] and [phase][@stdlib/math/base/special/cphase] of a double-precision complex floating-point number.

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

var o = cpolar( new Complex128( 5.0, 3.0 ) );
// returns [ ~5.83, ~0.5404 ]
```

#### cpolar.assign( z, out, stride, offset )

Computes the [absolute value][@stdlib/math/base/special/cabs] and [phase][@stdlib/math/base/special/cphase] of a double-precision complex floating-point number and assigns results to a provided output array.

```javascript
var Complex128 = require( '@stdlib/complex/float64' );
var Float64Array = require( '@stdlib/array/float64' );

var out = new Float64Array( 2 );

var v = cpolar.assign( new Complex128( 5.0, 3.0 ), out, 1, 0 );
// returns <Float64Array>[ ~5.83, ~0.5404 ]

var bool = ( v === out );
// returns true
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var Complex128 = require( '@stdlib/complex/float64' );
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var real = require( '@stdlib/complex/real' );
var imag = require( '@stdlib/complex/imag' );
var cpolar = require( '@stdlib/math/base/special/cpolar' );

var re;
var im;
var z;
var o;
var i;

for ( i = 0; i < 100; i++ ) {
    re = round( randu()*100.0 ) - 50.0;
    im = round( randu()*100.0 ) - 50.0;
    z = new Complex128( re, im );
    o = cpolar( z );
    z = z.toString();
    console.log( 'abs(%s) = %d. arg(%s) = %d', z, o[0], z, o[1] );
}
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- 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>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

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

#### stdlib_base_cpolar( z, cabs, cphase )

Computes the [absolute value][@stdlib/math/base/special/cabs] and [phase][@stdlib/math/base/special/cphase] of a double-precision complex floating-point number.

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

stdlib_complex128_t z = stdlib_complex128( 5.0, 3.0 );
double cabs;
double cphase;
stdlib_base_cpolar( z, &cabs, &cphase );
```

The function accepts the following arguments:

-   **z**: `[in] stdlib_complex128_t` input value.
-   **cabs**: `[out] double*` destination for the absolute value.
-   **cphase**: `[out] double*` destination for the phase value in radians.

```c
double stdlib_base_cpolar( const stdlib_complex128_t z, double *cabs, double *cphase );
```

</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/cpolar.h"
#include "stdlib/complex/float64.h"
#include "stdlib/complex/reim.h"
#include <stdio.h>

int main( void ) {
    const stdlib_complex128_t x[] = {
        stdlib_complex128( 3.14, 1.0 ),
        stdlib_complex128( -3.14, -1.0 ),
        stdlib_complex128( 0.0, 0.0 ),
        stdlib_complex128( 0.0/0.0, 0.0/0.0 )
    };

    double cphase;
    double cabs;
    double re;
    double im;
    int i;
    for ( i = 0; i < 12; i++ ) {
        stdlib_base_cpolar( x[i], &cabs, &cphase );
        stdlib_reim( x[i], &re, &im );
        printf( "cpolar(%lf + %lfi) => cabs: %lf, cphase: %lf\n", re, im, cabs, cphase );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/math/base/special/cabs`][@stdlib/math/base/special/cabs]</span><span class="delimiter">: </span><span class="description">compute the absolute value of a double-precision complex floating-point number.</span>
-   <span class="package-name">[`@stdlib/math/base/special/cphase`][@stdlib/math/base/special/cphase]</span><span class="delimiter">: </span><span class="description">compute the argument of a double-precision complex floating-point number in radians.</span>

</section>

<!-- /.related -->

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

<section class="links">

[@stdlib/math/base/special/cabs]: https://github.com/stdlib-js/math/tree/main/base/special/cabs

[@stdlib/math/base/special/cphase]: https://github.com/stdlib-js/math/tree/main/base/special/cphase

<!-- <related-links> -->

<!-- </related-links> -->

</section>

<!-- /.links -->
