Man page - erf(3)

Packages contains this manual

Available languages:

en fr pt_BR es pl cs ja ru ro de

Manual

erf

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
STANDARDS
HISTORY
SEE ALSO

NAME

erf, erff, erfl - error function

LIBRARY

Math library ( libm , -lm )

SYNOPSIS

#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

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 value of 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

For an explanation of the terms used in this section, see attributes (7).

Image grohtml-222232-1.png

STANDARDS

C11, POSIX.1-2008.

HISTORY

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD.

SEE ALSO

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