#include <math.h> double erf(double x); float erff(float x); long double erfl(long double x);Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
erf():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
erff(), erfl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
erf(x) = 2/sqrt(pi) * integral from 0 to x of exp(-t*t) dt
If x is a NaN, a NaN is returned.
If x is +0 (-0), +0 (-0) is returned.
If x is positive infinity (negative infinity), +1 (-1) is returned.
If x is subnormal, a range error occurs, and the return value is 2*x/sqrt(pi).
The following errors can occur:
These functions do not set errno.
Interface | Attribute | Value |
erf(), erff(), erfl() | Thread safety | MT-Safe |
The variant returning double also conforms to SVr4, 4.3BSD.