erf, erfc - error functions

 #include <math.h> 

 double erf(x)  double x; 

 double erfc(x)  double x; 

Erf\|(x) returns the error function of x; where

erf(x) = 2/sqrt(pi)\(**\|integral from 0 to x of exp(-t\(**t) dt. \} erf\|(x) := (2/\(sr\(*p)\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\|exp(-t\u\s82\s10\d)\|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).

intro(3M)