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# Absolute Value

> Compute an [absolute value][absolute-value] of a signed 32-bit integer.

<section class="intro">

The [absolute value][absolute-value] is defined as

<!-- <equation class="equation" label="eq:absolute_value" align="center" raw="|x| = \begin{cases} x & \textrm{if}\ x \geq 0 \\ -x & \textrm{if}\ x < 0\end{cases}" alt="Absolute value"> -->

<div class="equation" align="center" data-raw-text="|x| = \begin{cases} x &amp; \textrm{if}\ x \geq 0 \\ -x &amp; \textrm{if}\ x &lt; 0\end{cases}" data-equation="eq:absolute_value">
    <img src="https://cdn.rawgit.com/stdlib-js/stdlib/7e0a95722efd9c771b129597380c63dc6715508b/lib/node_modules/@stdlib/math/base/special/int32-abs/docs/img/equation_absolute_value.svg" alt="Absolute value">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="usage">

## Usage

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

#### labs( x )

Computes an [absolute value][absolute-value] of a signed 32-bit integer.

```javascript
var v = labs( -1|0 );
// returns 1

v = labs( 2|0 );
// returns 2

v = labs( 0|0 );
// returns 0
```

</section>

<!-- /.usage -->

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

<section class="notes">

## Notes

-   The implementation assumes two's complement.

-   In two's complement systems, the absolute value of the minimum signed 32-bit integer is out-of-range. The absolute value for the minimum signed 32-bit integer is thus undefined.

    ```javascript
    // -2^31
    var x = -2147483648|0;

    var v = labs( x );
    // returns -2147483648
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var labs = require( '@stdlib/math/base/special/labs' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 ) - 50;
    console.log( 'abs(%d) = %d', x, labs( x|0 ) );
}
```

</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/labs.h"
```

#### stdlib_base_labs( x )

Computes the absolute value of a signed 32-bit integer in two's complement format.

```c
#include <stdint.h>

int32_t y = stdlib_base_labs( -5 );
// returns 5
```

The function accepts the following arguments:

-   **x**: `[in] int32_t` input value.

```c
int32_t stdlib_base_labs( const int32_t x );
```

</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/labs.h"
#include <stdint.h>
#include <stdio.h>

int main() {
    int32_t x[] = { 3, -3, 0, -10 };

    int32_t y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_labs( x[ i ] );
        printf( "|%i| = %i\n", x[ i ], y );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<section class="links">

[absolute-value]: https://en.wikipedia.org/wiki/Absolute_value

</section>

<!-- /.links -->
