npm package: @stdlib/math-base-special-inv
Description: Compute the multiplicative inverse of a double-precision floating-point number.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
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    About stdlib...
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# inv

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

> Compute the [multiplicative inverse][multiplicative-inverse] of a double-precision floating-point number.

<section class="intro">

The [multiplicative inverse][multiplicative-inverse] (or **reciprocal**) is defined as

<!-- <equation class="equation" label="eq:multiplicative_inverse" align="center" raw="y = \frac{1}{x}" alt="Multiplicative inverse"> -->

<div class="equation" align="center" data-raw-text="y = \frac{1}{x}" data-equation="eq:multiplicative_inverse">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@bb29798906e119fcb2af99e94b60407a270c9b32/lib/node_modules/@stdlib/math/base/special/inv/docs/img/equation_multiplicative_inverse.svg" alt="Multiplicative inverse">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### inv( x )

Computes the [multiplicative inverse][multiplicative-inverse] of a double-precision floating-point number `x`.

```javascript
var v = inv( -1.0 );
// returns -1.0

v = inv( 2.0 );
// returns 0.5

v = inv( 0.0 );
// returns Infinity

v = inv( -0.0 );
// returns -Infinity

v = inv( 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 inv = require( '@stdlib/math-base-special-inv' );

var opts = {
    'dtype': 'float64'
};
var x = discreteUniform( 100, -50, 50, opts );

logEachMap( 'inv(%0.4f) = %0.4f', x, inv );
```

</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/inv.h"
```

#### stdlib_base_inv( x )

Computes the multiplicative inverse of a double-precision floating-point number.

```c
double y = stdlib_base_inv( 2.0 );
// returns 0.5
```

The function accepts the following arguments:

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

```c
double stdlib_base_inv( 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/special/inv.h"
#include <stdio.h>

int main( void ) {
    const double x[] = { 3.0, 4.0, 5.0, 12.0 };

    double y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_inv( x[ i ] );
        printf( "inv(%lf) = %lf\n", x[ i ], y );
    }
}
```

</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/special/pow`][@stdlib/math/base/special/pow]</span><span class="delimiter">: </span><span class="description">exponential function.</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="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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<section class="links">

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[npm-url]: https://npmjs.org/package/@stdlib/math-base-special-inv

[test-image]: https://github.com/stdlib-js/math-base-special-inv/actions/workflows/test.yml/badge.svg?branch=v0.2.3
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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-base-special-inv/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/math-base-special-inv?branch=main

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

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

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

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-special-inv/main/LICENSE

[multiplicative-inverse]: https://en.wikipedia.org/wiki/Multiplicative_inverse

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

[@stdlib/math/base/special/pow]: https://www.npmjs.com/package/@stdlib/math-base-special-pow

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

</section>

<!-- /.links -->