ERF
Section: Linux Programmer's Manual (3)
Updated: 2013-10-29
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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 ||
_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].
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.
ATTRIBUTES
Multithreading (see pthreads(7))
The
erf(),
erff(),
and
erfl()
functions are thread-safe.
CONFORMING TO
C99, POSIX.1-2001.
The variant returning
double
also conforms to
SVr4, 4.3BSD.
SEE ALSO
cerf(3),
erfc(3),
exp(3)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- Multithreading (see pthreads(7))
-
- CONFORMING TO
-
- SEE ALSO
-
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Time: 02:55:15 GMT, September 18, 2014