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# isNegativeInteger

> Test if a finite [double-precision floating-point number][ieee754] is a negative integer.

<section class="usage">

## Usage

```javascript
var isNegativeInteger = require( '@stdlib/math/base/assert/is-negative-integer' );
```

#### isNegativeInteger( x )

Tests if a finite [double-precision floating-point number][ieee754] is a negative `integer`.

```javascript
var bool = isNegativeInteger( -1.0 );
// returns true

bool = isNegativeInteger( 0.0 );
// returns false

bool = isNegativeInteger( 10.0 );
// returns false
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   The function assumes a **finite** `number`. If provided 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 &&
            isNegativeInteger( x )
        );
    }

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

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var isNegativeInteger = require( '@stdlib/math/base/assert/is-negative-integer' );

var bool = isNegativeInteger( -5.0 );
// returns true

bool = isNegativeInteger( 0.0 );
// returns false

bool = isNegativeInteger( 1.0 );
// returns false

bool = isNegativeInteger( -3.14 );
// returns false

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

</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_negative_integer.h"
```

#### stdlib_base_is_negative_integer( x )

Tests if a finite [double-precision floating-point number][ieee754] is a negative integer.

```c
#include <stdbool.h>

bool out = stdlib_base_is_negative_integer( -4.0 );
// returns true

out = stdlib_base_is_negative_integer( 3.0 );
// returns false
```

The function accepts the following arguments:

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

```c
bool stdlib_base_is_negative_integer( 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_negative_integer.h"
#include <stdio.h>
#include <stdbool.h>

int main( void ) {
    const double x[] = { 5.0, -5.0, 3.14, -3.14, 0.0, 0.0/0.0 };

    bool b;
    int i;
    for ( i = 0; i < 6; i++ ) {
        b = stdlib_base_is_negative_integer( x[ i ] );
        printf( "Value: %lf. Is negative integer? %s.\n", x[ i ], ( b ) ? "True" : "False" );
    }
}
```

</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-integer`][@stdlib/math/base/assert/is-integer]</span><span class="delimiter">: </span><span class="description">test if a finite double-precision floating-point number is an integer.</span>
-   <span class="package-name">[`@stdlib/math/base/assert/is-nonnegative-integer`][@stdlib/math/base/assert/is-nonnegative-integer]</span><span class="delimiter">: </span><span class="description">test if a finite double-precision floating-point number is a nonnegative integer.</span>
-   <span class="package-name">[`@stdlib/math/base/assert/is-nonpositive-integer`][@stdlib/math/base/assert/is-nonpositive-integer]</span><span class="delimiter">: </span><span class="description">test if a finite double-precision floating-point number is a nonpositive integer.</span>
-   <span class="package-name">[`@stdlib/math/base/assert/is-positive-integer`][@stdlib/math/base/assert/is-positive-integer]</span><span class="delimiter">: </span><span class="description">test if a finite double-precision floating-point number is a positive integer.</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">

[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985

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

[@stdlib/math/base/assert/is-integer]: https://github.com/stdlib-js/math/tree/main/base/assert/is-integer

[@stdlib/math/base/assert/is-nonnegative-integer]: https://github.com/stdlib-js/math/tree/main/base/assert/is-nonnegative-integer

[@stdlib/math/base/assert/is-nonpositive-integer]: https://github.com/stdlib-js/math/tree/main/base/assert/is-nonpositive-integer

[@stdlib/math/base/assert/is-positive-integer]: https://github.com/stdlib-js/math/tree/main/base/assert/is-positive-integer

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

</section>

<!-- /.links -->
