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exp

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

Natural [exponential function][exponential-function].

The natural [exponential function][exponential-function] is defined as

math
y = e^x

where e is [Euler’s][@stdlib/constants/float64/e] number.

## Installation

bash
npm install @stdlib/math-base-special-exp

Alternatively,

- To load the package in a website via a script tag without installation and bundlers, use the [ES Module][es-module] available on the [esm][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [deno][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [umd][umd-url] branch (see [README][umd-readme]).

The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

## Usage

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

#### exp( x )

Evaluates the natural [exponential function][exponential-function].

javascript
var v = exp( 4.0 );
// returns ~54.5982

v = exp( -9.0 );
// returns ~1.234e-4

v = exp( 0.0 );
// returns 1.0

v = exp( NaN );
// returns NaN

## Examples

javascript
var randu = require( '@stdlib/random-base-randu' );
var exp = require( '@stdlib/math-base-special-exp' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = (randu()*100.0) - 50.0;
    console.log( 'e^%d = %d', x, exp( x ) );
}

## C APIs

### Usage

c
#include "stdlib/math/base/special/exp.h"

#### stdlib_base_exp( x )

Evaluates the natural [exponential function][exponential-function].

c
double out = stdlib_base_exp( 4.0 );
// returns ~54.5982

out = stdlib_base_exp( -9.0 );
// returns ~1.234e-4

The function accepts the following arguments:

- x: [in] double input value.

c
double stdlib_base_exp( const double x );

### Examples

c
#include "stdlib/math/base/special/exp.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 ) * 100.0;
        v = stdlib_base_exp( x );
        printf( "e^%lf = %lf\n", x, v );
    }
}

*

## 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]

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## Copyright

Copyright © 2016-2025. The Stdlib [Authors][stdlib-authors].