NAME
erf, erff, erfl, - error function
SYNOPSIS
#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;
or cc -std=c99
erff(), erfl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600||
_ISOC99_SOURCE; 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].
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).
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 3.24 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/.