npm package: @stdlib/math-base-assert-is-even
Description: Test if a finite numeric value is an even number.
Author: The Stdlib Authors
Latest version: 0.2.5

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# isEven

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> Test if a finite numeric value is an even number.

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-assert-is-even
```

</section>

<section class="usage">

## Usage

```javascript
var isEven = require( '@stdlib/math-base-assert-is-even' );
```

#### isEven( x )

Tests if a **finite** `numeric` value is an even number.

```javascript
var bool = isEven( 5.0 );
// returns false

bool = isEven( -2.0 );
// returns true

bool = isEven( 0.0 );
// returns true

bool = isEven( NaN );
// returns false
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   The function assumes a **finite** `number`. If provided positive or negative `infinity`, the function will return `true`, when, in fact, the result is undefined. If `x` can be `infinite`, wrap the implementation as follows:

    ```javascript
    function check( x ) {
        return (
            x < Infinity &&
            x > -Infinity &&
            isEven( x )
        );
    }

    var bool = check( Infinity );
    // returns false

    bool = check( -Infinity );
    // returns false
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var isEven = require( '@stdlib/math-base-assert-is-even' );

var opts = {
    'dtype': 'float64'
};
var x = discreteUniform( 100, 0, 100, opts );

function isEvenWrapper( integer ) {
    return ( isEven( integer ) ) ? 'even' : 'not even';
}
logEachMap( '%d is %s', x, isEvenWrapper );
```

</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/assert/is_even.h"
```

#### stdlib_base_is_even( x )

Tests if a finite numeric value is an even number.

```c
bool out = stdlib_base_is_even( 1.0 );
// returns false

out = stdlib_base_is_even( 4.0 );
// returns true
```

The function accepts the following arguments:

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

```c
bool stdlib_base_is_even( const double 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/assert/is_even.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

int main( void ) {
    double x;
    bool v;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( ( (double)rand() / (double)RAND_MAX ) * 100.0 );
        v = stdlib_base_is_even( x );
        printf( "x = %lf, is_even(x) = %s\n", x, ( v ) ? "even" : "not even" );
    }
}
```

</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/assert/is-odd`][@stdlib/math/base/assert/is-odd]</span><span class="delimiter">: </span><span class="description">test if a finite numeric value is an odd number.</span>

</section>

<!-- /.related -->

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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

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

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

</section>

<!-- /.stdlib -->

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

[@stdlib/math/base/assert/is-odd]: https://www.npmjs.com/package/@stdlib/math-base-assert-is-odd

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</section>

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