3курс / вегстейн

uses crt;
const
a=1;b=3; epsilon=0.000001;
var
root:real;
kolit:integer;
function f(t:real):real;
begin
f:=t*sqr(sqr(t))-8*t-1;
end;

function phi(x:real):real;
begin
phi:=x+f(x);
end;
procedure Iter(a,b:real;var x2,y2:real; var flag:Boolean);
var
x0,x1,y0,y1:real;
begin
kolit:=kolit+1;
x0:=a;y0:=phi(x0);
x1:=b;y1:=phi(x1);
x2:=(x1*y0-y1*x0)/((x1-x0)-(y1-y0));
writeln(a,b,x2);
y2:=phi(x2);
flag:=(y0-x0)*(y2-x2)>0;
end;
procedure Vegstein(a,b,eps:real; var x:real);
var
xz,yz:real;
prizn:Boolean;
begin
repeat
Iter(a,b,xz,yz,prizn);
if prizn then a:=xz else b:=xz;
until abs(xz-yz)<eps;
writeln('корень===',xz);
x:=xz;
end;
begin
kolit:=0;
vegstein(a,b,epsilon,root);
writeln('число шагов',kolit:6);

end.