{  (C) Copr. 1986-92 Numerical Recipes Software .5-28.}

{ Функция ошибок }
unit uErf;

interface

function Erf(x:Double):Double;

function Erfc(x:Double):Double;

implementation
  USES uGamma;

function Erf(x:Double):Double;
begin
 if x<0 then erf:=-gammp(0.5, x*x)
	else erf:= gammp(0.5, x*x);
end;


function Erfc(x:Double):Double;
  var f,t,z:Double;
begin
  z:=abs(x);
  t:=1./(1.+0.5*z);
  f:=t*exp(-z*z-1.26551223+
	  t*(1.00002368+
	     t*(0.37409196+
		t*(0.09678418+
		   t*(-0.18628806+
		      t*(0.27886807+
			 t*(-1.13520398+
			    t*(1.48851587+
			       t*(-0.82215223+
				  t*0.17087277)))))))));
  if (x<0) then erfc:=2.-f else erfc:=f;
end;

END.