exp(3) Linux Man Page - System Grab Bag

Name

exp, expf, expl - base-e exponential function

Library

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 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.

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ exp()expf()expl()

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.