npm package: @stdlib/math-base-special-lnf
Description: Evaluate the natural logarithm of a single-precision floating-point number.
Author: The Stdlib Authors
Latest version: 0.0.4

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# lnf

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

> Evaluate the [natural logarithm][natural-logarithm] of a single-precision floating-point number.

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### lnf( x )

Evaluates the [natural logarithm][natural-logarithm] of a single-precision floating-point number.

```javascript
var v = lnf( 4.0 );
// returns ~1.386

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

v = lnf( Infinity );
// returns Infinity

v = lnf( NaN );
// returns NaN
```

For negative numbers, the [natural logarithm][natural-logarithm] is **not** defined.

```javascript
var v = lnf( -4.0 );
// 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 lnf = require( '@stdlib/math-base-special-lnf' );

var opts = {
    'dtype': 'float32'
};
var x = discreteUniform( 100, 0, 100, opts );

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

</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/lnf.h"
```

#### stdlib_base_lnf( x )

Evaluates the [natural logarithm][natural-logarithm] of a single-precision floating-point number.

```c
float v = stdlib_base_lnf( 2.0f );
// returns ~0.693f
```

The function accepts the following arguments:

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

```c
float stdlib_base_lnf( const float 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/lnf.h"
#include <stdlib.h>
#include <stdio.h>

int main( void ) {
    float out;
    float x;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( (float)rand() / (float)RAND_MAX ) * 100.0f;
        out = stdlib_base_lnf( x );
        printf( "lnf(%f) = %f\n", x, 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

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---

## Copyright

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

</section>

<!-- /.stdlib -->

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

[natural-logarithm]: https://en.wikipedia.org/wiki/Natural_logarithm

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</section>

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