bsd man page for erfc

ERF(3M) 																   ERF(3M)

NAME
       erf, erfc - error functions

SYNOPSIS
       #include <math.h>

       double erf(x)
       double x;

       double erfc(x)
       double x;

DESCRIPTION
       Erf(x) returns the error function of x; where

       erf(x) = 2/sqrt(pi)*integral from 0 to x of exp(-t*t) dt.

       Erfc(x) returns 1.0-erf(x).

       The  entry  for erfc is provided because of the extreme loss of relative accuracy if erf(x) is called for large x and the result subtracted
       from 1.	(e.g. for x = 10, 12 places are lost).

SEE ALSO
       math(3M)

4.3 Berkeley Distribution					   May 12, 1986 							   ERF(3M)