program Liczba_pi_Algorytm_Gaussa_Legendrea;
{$N+}
uses crt;
var a, b, t, x, y:extended;
begin
  clrScr;
  a:=1; b:=1/sqrt(2); t:=1/4; x:=1;
  writeLn(a:22:18,b:22:18,t:22:18);
  writeLn('pi=',(a+b)*(a+b)/(4*t):22:18);
  repeat
    y:=a;
    a:=(a+b)/2;
    b:=sqrt(b*y);
    t:=t-x*(y-a)*(y-a);
    x:=2*x;
    writeLn(a:22:18,b:22:18,t:22:18);
    writeLn('pi=',(a+b)*(a+b)/(4*t):22:18);
  until a-b<0.0000000000000000001;
  writeln('pi=',pi:22:18);
  readLn;
end.