ERF(3) | Linux Programmer's Manual | ERF(3) |
NAME
erf, erff, erfl, - error functionSYNOPSIS
#include<math.h>
double erf(double x);
float erff(float x);
long double erfl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
erf():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or
cc -std=c99
erff(), erfl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or
cc -std=c99
DESCRIPTION
The erf() function returns the error function of x, defined as-
erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(-t*t) dt
RETURN VALUE
On success, these functions return the error function of x, a value in the range [-1, 1].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 ( x 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.SEE ALSO
cerf(3), erfc(3), exp(3)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2010-09-20 | GNU |