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[thirdparty/man-pages.git] / man3 / exp.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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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 (faith@cs.unc.edu)
.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
.\" Modified 2002-07-27 by Walter Harms
.\" 	(walter.harms@informatik.uni-oldenburg.de)
.\"
.TH EXP 3  2015-03-02  "" "Linux Programmer's Manual"
.SH NAME
exp, expf, expl \- base-e exponential function
.SH SYNOPSIS
.nf
.B #include <math.h>
.sp
.BI "double exp(double " x );
.br
.BI "float expf(float " x );
.br
.BI "long double expl(long double " x );
.fi
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR expf (),
.BR expl ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad b
.SH DESCRIPTION
The
.BR exp ()
function returns the value of e (the base of natural
logarithms) raised to the power of
.IR x .
.SH RETURN VALUE
On success, these functions return the exponential value of
.IR x .

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

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

If
.I 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
.RB + HUGE_VAL ,
.RB + HUGE_VALF ,
or
.RB + HUGE_VALL ,
respectively.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.

The following errors can occur:
.TP
Range error, overflow
.I errno
is set to
.BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.TP
Range error, underflow
.I errno
is set to
.BR ERANGE .
An underflow floating-point exception
.RB ( FE_UNDERFLOW )
is raised.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw21 lb lb
l l l.
Interface	Attribute	Value
T{
.BR exp (),
.BR expf (),
.BR expl ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.

The variant returning
.I double
also conforms to
SVr4, 4.3BSD, C89.
.SH SEE ALSO
.BR cbrt (3),
.BR cexp (3),
.BR exp10 (3),
.BR exp2 (3),
.BR sqrt (3)