npm package: @stdlib/math-base-special-logit
Description: Logit function.
Author: The Stdlib Authors
Latest version: 0.2.4

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</details>

# logit

[![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 [logit][logit] function.

<section class="intro">

The [logit][logit] function is defined as the logarithm of the odds `p / (1-p)`; i.e.,

<!-- <equation class="equation" label="eq:logit_function" align="center" raw="\operatorname{logit}(p)=\log \left({\frac {p}{1-p}}\right)" alt="Logit function."> -->

<div class="equation" align="center" data-raw-text="\operatorname{logit}(p)=\log \left({\frac {p}{1-p}}\right)" data-equation="eq:logit_function">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@bb29798906e119fcb2af99e94b60407a270c9b32/lib/node_modules/@stdlib/math/base/special/logit/docs/img/equation_logit_function.svg" alt="Logit function.">
    <br>
</div>

<!-- </equation> -->

The [logit][logit] function is the inverse of the [standard logistic][standard-logistic] function, sometimes also called the sigmoid function.

</section>

<!-- /.intro -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### logit( p )

Computes the [logit][logit] function.

```javascript
var v = logit( 0.2 );
// returns ~-1.386

v = logit( 0.9 );
// returns ~2.197
```

If `p < 0` or `p > 1`, the function returns `NaN`.

```javascript
var v = logit( 1.3 );
// returns NaN

v = logit( -0.2 );
// returns NaN
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var logit = require( '@stdlib/math-base-special-logit' );

var opts = {
    'dtype': 'float64'
};
var p = uniform( 100, 0.0, 1.0, opts );

logEachMap( 'logit(%0.4f) = %0.4f', p, logit );
```

</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/logit.h"
```

#### stdlib_base_logit( p )

Computes the [logit][logit] function.

```c
double out = stdlib_base_logit( 0.2 );
// returns ~-1.386

out = stdlib_base_logit( 0.9 );
// returns ~2.197
```

The function accepts the following arguments:

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

```c
double stdlib_base_logit( const double p );
```

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

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

    for ( i = 0; i < 100; i++ ) {
        x = (double)rand() / (double)RAND_MAX;
        v = stdlib_base_logit( x );
        printf( "logit(%lf) = %lf\n", x, v );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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

<section class="related">

</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-logit

[test-image]: https://github.com/stdlib-js/math-base-special-logit/actions/workflows/test.yml/badge.svg?branch=v0.2.4
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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-base-special-logit/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/math-base-special-logit?branch=main

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

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

[logit]: https://en.wikipedia.org/wiki/Logit

[standard-logistic]: https://en.wikipedia.org/wiki/Logistic_function

</section>

<!-- /.links -->