ERFC
Section: Linux Programmer's Manual (3)
Updated: 20131029
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NAME
erfc, erfcf, erfcl  complementary error function
SYNOPSIS
#include <math.h>
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);
Link with
lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
erfc():

_BSD_SOURCE  _SVID_SOURCE  _XOPEN_SOURCE  _ISOC99_SOURCE 
_POSIX_C_SOURCE >= 200112L;
or
cc std=c99
erfcf(),
erfcl():

_BSD_SOURCE  _SVID_SOURCE  _XOPEN_SOURCE >= 600 _ISOC99_SOURCE 
_POSIX_C_SOURCE >= 200112L;
or
cc std=c99
DESCRIPTION
The
erfc()
function returns the complementary error function of
x,
that is, 1.0  erf(x).
RETURN VALUE
On success, these functions return the complementary error function of
x,
a value in the range [0,2].
If
x
is a NaN, a NaN is returned.
If
x
is +0 or 0, 1 is returned.
If
x
is positive infinity,
+0 is returned.
If
x
is negative infinity,
+2 is returned.
If the function result underflows and produces an unrepresentable value,
the return value is 0.0.
If the function result underflows but produces a representable
(i.e., subnormal) value,
that value is returned, and
a range error occurs.
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: result underflow (result is subnormal)

An underflow floatingpoint exception
(FE_UNDERFLOW)
is raised.
These functions do not set
errno.
ATTRIBUTES
Multithreading (see pthreads(7))
The
erfc(),
erfcf(),
and
erfcl()
functions are threadsafe.
CONFORMING TO
C99, POSIX.12001.
The variant returning
double
also conforms to
SVr4, 4.3BSD.
NOTES
The
erfc(),
erfcf(),
and
erfcl()
functions are provided to avoid the loss accuracy that
would occur for the calculation 1erf(x) for large values of
x
(for which the value of erf(x) approaches 1).
SEE ALSO
cerf(3),
erf(3),
exp(3)
COLOPHON
This page is part of release 3.74 of the Linux
manpages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
http://www.kernel.org/doc/manpages/.
Index
 NAME

 SYNOPSIS

 DESCRIPTION

 RETURN VALUE

 ERRORS

 ATTRIBUTES

 Multithreading (see pthreads(7))

 CONFORMING TO

 NOTES

 SEE ALSO

 COLOPHON
