erfc (3) Linux Manual Page
erfc, erfcf, erfcl – complementary error function
Synopsis
#include <math.h>Link with -lm.
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
erfc():
- _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
erfcf(), erfcl():
- _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Description
These functions return 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.
Attributes
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| erfc(), erfcf(), erfcl() | Thread safety | MT-Safe |
Conforming To
C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD.