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ERF(3)                     Linux Programmer's Manual                    ERF(3)

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.
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)