Manpage of ERF

ERF

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

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():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

erff(), erfl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
 

DESCRIPTION

These functions return 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 xis a NaN, a NaN is returned.

If xis +0 (-0), +0 (-0) is returned.

If xis positive infinity (negative infinity), +1 (-1) is returned.

If xis 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

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
erf(), erff(), erfl() Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning doublealso conforms to SVr4, 4.3BSD.  

SEE ALSO

cerf(3), erfc(3), exp(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
SEE ALSO

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Time: 22:27:58 GMT, June 20, 2016