Name
erfc, erfcf, erfcl - complementary error functionLibrary
Math library ( libm ", " -lm )Synopsis
#include <math.h> 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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
erfcf() erfcl()
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Description
These functions return the complementary error function ofx, that is, 1.0 - erf(x). Return Value
On success, these functions return the complementary error function ofx, 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 |
| T} | Thread safety | MT-Safe |
Standards
C11, POSIX.1-2008.History
C99, POSIX.1-2001.The variant returning double also conforms to SVr4, 4.3BSD.