---
name: "exp2"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/exp2"
---

# exp2(3)

base-2 exponential function

## NAME

exp2, exp2f, exp2l - base-2 exponential function

## LIBRARY

Math library (*libm*, *-lm*)

## SYNOPSIS

```
#include <math.h>
```

**double exp2(double** *x***);** **float exp2f(float** *x***);** **long double exp2l(long double** *x***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**exp2**(), **exp2f**(), **exp2l**():

```
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
```

## DESCRIPTION

These functions return the value of 2 raised to the power of *x*.

## RETURN VALUE

On success, these functions return the base-2 exponential value of *x*.

For various special cases, including the handling of infinity and NaN, as well as overflows and underflows, see [**exp**(3)](/exp/3.md).

## ERRORS

See [**math\_error**(7)](/math_error/7.md) for information on how to determine whether an error has occurred when calling these functions.

For a discussion of the errors that can occur for these functions, see [**exp**(3)](/exp/3.md).

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **exp2**(), **exp2f**(), **exp2l**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

glibc 2.1. C99, POSIX.1-2001.

The variant returning *double* also conforms to SVr4, 4.3BSD.

## SEE ALSO

[**cbrt**(3)](/cbrt/3.md), [**cexp2**(3)](/cexp2/3.md), [**exp**(3)](/exp/3.md), [**exp10**(3)](/exp10/3.md), [**sqrt**(3)](/sqrt/3.md)