erf(3)

NAME
     erf, erfc - error functions

SYNOPSIS
     #include <math.h>

     double erf(double x)
     double erfc(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(3).