### NAME

exp, expf, expl - base-e exponential function

### SYNOPSIS

**#include <math.h>**

**double exp(double ***x***);**
**float expf(float ***x***);**
**long double expl(long double ***x***);**

Link with *-lm*.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

**expf**(), **expl**(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or
*cc -std=c99*

### DESCRIPTION

The
**exp**() function returns the value of e (the base of natural
logarithms) raised to the power of *x*.

### RETURN VALUE

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

If
*x* is a NaN,
a NaN is returned.

If
*x* is positive infinity,
positive infinity is returned.

If
*x* is negative infinity,
+0 is returned.

If the result underflows, a range error occurs, and zero is returned.

If the result overflows,
a range error occurs,
and the functions return
+**HUGE_VAL**, +**HUGE_VALF**, or
+**HUGE_VALL**, respectively.

### ERRORS

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Range error, overflow | |

errno is set to
ERANGE. An overflow floating-point exception
(FE_OVERFLOW) is raised.
| |

Range error, underflow | |

errno is set to
ERANGE. An underflow floating-point exception
(FE_UNDERFLOW) is raised.
| |

### CONFORMING TO

C99, POSIX.1-2001.
The variant returning
*double* also conforms to
SVr4, 4.3BSD, C89.

### SEE ALSO

cbrt(3), cexp(3), exp10(3), exp2(3), sqrt(3)

### COLOPHON

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*man-pages* project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.