ultrix man page for erf

erf(3m) 																   erf(3m)

Name
       erf, erfc - error functions

Syntax
       #include <math.h>

       double erf(x)
       double x;

       double erfc(x)
       double x;

Description
       The function returns the error function of x defined as follows:
       erf(x) = 2/sqrt(pi)*integral from 0 to x of exp(-t*t) dt.

       The function returns 1.0-erf(x).

       The entry for the function is provided because of the extreme loss of relative accuracy if erf(x) is called for large x and the result sub-
       tracted from 1.	For example if x = 10, 12 places are lost.

Return Values
       The and functions return NaN when x is NaN.

See Also
       math(3m)

								       RISC								   erf(3m)