ERFC(3) Linux Programmer's Manual ERFC(3)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 floating-point exception (FE_UNDERFLOW) is raised.
These functions do not set errno.
CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
4.3BSD.
NOTES
The erfc() functions are provided to avoid the loss accuracy that would
occur for the calculation 1-erf(x) for large values of x (for which the
value of erf(x) approaches 1).
SEE ALSOcerf(3), erf(3), exp(3)COLOPHON
This page is part of release 3.35 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://man7.org/linux/man-pages/.
GNU 2010-09-20 ERFC(3)
