npm package: @stdlib/math-base-assert-is-negative-integer
Description: Test if a finite double-precision floating-point number is a negative integer.
Author: The Stdlib Authors
Latest version: 0.3.2

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# isNegativeInteger

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

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

<section class="installation">

## Installation

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

</section>

<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 -->

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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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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-assert-is-negative-integer/main/LICENSE

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

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

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

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

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