Linux manual pages Section 3  

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);
 
[Note] Note
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 versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE
[Note] Note

Link with −lm.

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).

Interface Attribute Value
exp(), expf(), expl() Thread safety MT-Safe

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO

cbrt(3), cexp(3), exp10(3), exp2(3), expm1(3), sqrt(3)

COLOPHON

This page is part of release 4.07 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man−pages/.


  Copyright 1993 David Metcalfe (davidprism.demon.co.uk)
and Copyright 2008, Linux Foundation, written by Michael Kerrisk
    <mtk.manpagesgmail.com>

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References consulted:
    Linux libc source code
    Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
    386BSD man pages
Modified 1993-07-24 by Rik Faith (faithcs.unc.edu)
Modified 1995-08-14 by Arnt Gulbrandsen <agulbratroll.no>
Modified 2002-07-27 by Walter Harms
(walter.harmsinformatik.uni-oldenburg.de)