erf(), erfc() - error function operators
#include <math.h>
double erf (double x)
double erfc (double x)
These functions calculate the error function of x.
The erf(3) calculates the error function of x; where erf(x) = 2/sqrt(pi)*integral from 0 to x of exp(-t*t) dt.
The erfc(3) function calculates the complementary error function of x; that is erfc(3) subtracts the result of the error function erf(x) from 1.0. This is useful, since for large x places disappear.
math(3)