# erf(3) [centos man page]

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 withFeature 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-lm.erff(), erfl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc-std=c99-std=c99DESCRIPTION

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) dtRETURN VALUE

On success, these functions return the error function of x, a value in the range [, 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).-1ERRORS

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/.GNU

2010-09-20 ERF(3)

## Check Out this Related Man Page

ERFC(3) Linux Programmer's Manual ERFC(3)NAME

erfc, erfcf, erfcl - complementary error functionSYNOPSIS

#include <math.h> double erfc(double x); float erfcf(float x); long double erfcl(long double x); Link withFeature Test Macro Requirements for glibc (see feature_test_macros(7)): erfc(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc-lm.erfcf(), erfcl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600|| _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc-std=c99-std=c99DESCRIPTION

The erfc() function returns the complementary error function of x, that is, 1.0 - erf(x).RETURN VALUE

On success, these functions return the complementary error function of x, a value in the range [0,2]. If x is a NaN, a NaN is returned. If x is +0 or, 1 is returned. If x is positive infinity, +0 is returned. If x is negative infinity, +2 is returned. If the function result underflows and produces an unrepresentable value, the return value is 0.0. If the function result underflows but produces a representable (i.e., subnormal) value, that value is returned, and a range error occurs.-0ERRORS

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 (result 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.NOTES

The erfc() functions are provided to avoid the loss accuracy that would occur for the calculation 1-erf(x) for large values of x (for which the value of erf(x) approaches 1).SEE ALSO

cerf(3), erf(3), exp(3)COLOPHON

This page is part of release 3.27 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/.GNU

2010-09-20 ERFC(3)