npm package: @stdlib/math-base-special-log1pf
Description: Evaluate the natural logarithm of 1+x as a single-precision floating-point number.
Author: The Stdlib Authors
Latest version: 0.1.1

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# log1pf

[![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][@stdlib/math/base/special/lnf] of `1+x` as a single‐precision floating-point number.

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-special-log1pf
```

</section>

<section class="usage">

## Usage

```javascript
var log1pf = require( '@stdlib/math-base-special-log1pf' );
```

#### log1pf( x )

Evaluates the [natural logarithm][@stdlib/math/base/special/lnf] of `1+x` as a single‐precision floating-point number.

```javascript
var v = log1pf( 4.0 );
// returns ~1.609

v = log1pf( -1.0 );
// returns -Infinity

v = log1pf( Infinity );
// returns Infinity

v = log1pf( 0.0 );
// returns 0.0

v = log1pf( -0.0 );
// returns -0.0

v = log1pf( NaN );
// returns NaN
```

For `x < -1`, the function returns `NaN`, as the [natural logarithm][@stdlib/math/base/special/lnf] is **not** defined for negative numbers.

```javascript
var v = log1pf( -2.0 );
// 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 log1pf = require( '@stdlib/math-base-special-log1pf' );

var opts = {
    'dtype': 'float32'
};
var x = uniform( 100, 0.0, 100.0, opts );

logEachMap( 'log1pf(%0.4f) = %0.4f', x, log1pf );
```

</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/log1pf.h"
```

#### stdlib_base_log1pf( x )

Evaluates the [natural logarithm][@stdlib/math/base/special/lnf] of `1+x` as a single‐precision floating-point number.

```c
float out = stdlib_base_log1pf( 4.0f );
// returns ~1.609f

out = stdlib_base_log1pf( -1.0f );
// returns -Infinity
```

The function accepts the following arguments:

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

```c
float stdlib_base_log1pf( 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/log1pf.h"
#include <stdlib.h>
#include <stdio.h>

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

    for ( i = 0; i < 100; i++ ) {
        x = ( (float)rand() / (float)RAND_MAX ) * 100.0f;
        v = stdlib_base_log1pf( x );
        printf( "log1pf(%f) = %f\n", x, v );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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<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-log1pf/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-log1pf/blob/deno/README.md
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[@stdlib/math/base/special/lnf]: https://www.npmjs.com/package/@stdlib/math-base-special-lnf

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