npm package: @stdlib/math-base-special-fmod
Description: Modulus function.
Author: The Stdlib Authors
Latest version: 0.1.1

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# Modulus Function

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

> [Modulus function][modulus-function].

<section class="intro">

The [modulus function][modulus-function] is defined as

<!-- <equation class="equation" label="eq:modulus_function" align="center" raw="z = x%y" alt="Modulus function"> -->

<!-- </equation> -->

where `x` is the **dividend** and `y` is the **divisor**.

</section>

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<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-special-fmod
```

</section>

<section class="usage">

## Usage

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

#### fmod( x, y )

Evaluates the [modulus function][modulus-function].

```javascript
var v = fmod( 8.0, 3.0 );
// returns 2.0

v = fmod( 9.0, 3.0 );
// returns 0.0

v = fmod( 8.9, 3.0 );
// returns 2.9

v = fmod( NaN, 3.0 );
// returns NaN

v = fmod( 5.0, NaN );
// returns NaN

v = fmod( NaN, NaN );
// returns NaN
```

</section>

<!-- /.usage -->

<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 fmod = require( '@stdlib/math-base-special-fmod' );

var opts = {
    'dtype': 'float64'
};
var x = discreteUniform( 100, 0, 10, opts );
var y = discreteUniform( 100, -5, 5, opts );

logEachMap( '%d%%%d = %d', x, y, fmod );
```

</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/fmod.h"
```

#### stdlib_base_fmod( x, y )

Evaluates the modulus function.

```c
double out = stdlib_base_fmod( 8.9, 3.0 );
// returns 2.9

out = stdlib_base_fmod( 4.0, 2.0 );
// returns 0.0
```

The function accepts the following arguments:

-   **x**: `[in] double` dividend.
-   **y**: `[in] double` divisor.

```c
double stdlib_base_fmod( const double x, const double y );
```

</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/fmod.h"
#include <stdlib.h>
#include <stdio.h>

int main( void ) {
    double out;
    double x;
    double y;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( ( (double)rand() / (double)RAND_MAX ) * 10.0 );
        y = ( ( (double)rand() / (double)RAND_MAX ) * 10.0 ) - 5.0;
        out = stdlib_base_fmod( x, y );
        printf( "fmod(%lf, %lf) = %lf\n", x, y, out );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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

<section class="related">

</section>

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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]

---

## Copyright

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

</section>

<!-- /.stdlib -->

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[stdlib]: https://github.com/stdlib-js/stdlib

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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/math-base-special-fmod/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-fmod/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-fmod/tree/umd
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[branches-url]: https://github.com/stdlib-js/math-base-special-fmod/blob/main/branches.md

[modulus-function]: https://en.wikipedia.org/wiki/Remainder

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</section>

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