erf,  erfc  - error function and complementary error func­
       tion


SYNOPSIS

       #include <math.h>

       double erf(double x);

       double erfc (double x);


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

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


CONFORMING TO

       SVID 3, BSD 4.3


SEE ALSO

       exp(3)