Name
exp, expf, expl - base-e exponential functionLibrary
Math library ( libm ", " -lm )Synopsis
#include <math.h> double exp(double x );
float expf(float x );
long double expl(long double x );
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
expf() expl()
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Description
These functions return the value of e (the base of natural logarithms) raised to the power ofx
. Return Value
On success, these functions return the exponential value ofx
. 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.
Attributes
For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |
T} | Thread safety | MT-Safe |
Standards
C11, POSIX.1-2008.History
C99, POSIX.1-2001.The variant returning double also conforms to SVr4, 4.3BSD, C89.