Как исправить ошибку?

procedure TForm1.Button1Click(Sender: TObject);
var V,z,y,h:real;
i,z1,z2,n,m:integer;
begin
  Label3.Caption:=#9+'     P'+#9+#9+'|'+#9+'     z'+#13;
h:=0.9;
z:=-5;
z1:=-5;
z2:=5;
n:=round((z2-z1)/h);
m:=n +1;
For i:=1 To m  Do
begin
If (z<pi) and (z>pi/2) then
begin
y:=1.2-4*sin(z);
end
else
if abs(z)<1 then
begin
y:=ln(1.8+z);
end
else
y:=z*exp((1/5)*ln(7.3-z));
V:=cos(0.2*(exp((1/3)*ln(y+3.6))))*exp(12.3-Abs(y)*ln(2));
Label3.Caption:=Label3.Caption+#9+format('%7.3f',[V])+#9+#9+'|'+#9+format('%7.3f',[z])+#13;
form1.Series1.AddXY(z,V);
z:=z+h;
end;
end;
 
procedure TForm1.btn1Click(Sender: TObject);
var V,z,y,h:real;
begin
 Label3.Caption:=#9+'     P'+#9+#9+'|'+#9+'     z'+#13;
h:=0.9;
z:=-5;
while z<=5 do
begin
if(z<pi) and (z>pi/2) then
begin
y:=1.2-4*Sin(z);
end
else
if abs(z)<1 then
begin
y:=ln(1.8+z);
end
else
y:=z*exp((1/5)*ln(7.3-z));
V:=cos(0.2*(exp((1/3)*ln(y+3.6))))*exp(12.3-Abs(y)*ln(2));
Label3.Caption:=Label3.Caption+'. '+#9+format('%7.3f',[V])+#9+#9+'|'+'. '+#9+format('%7.3f',[z])+#13;
form1.lnsrsSeries2.AddXY(z,V);
z:=z+h;
end;
end;
 
procedure TForm1.btn2Click(Sender: TObject);
var V,z,y,h:real;
begin
   Label3.Caption:=#9+'     P'+#9+#9+'|'+#9+'     z'+#13;
h:=0.4;
z:=-5;
repeat
if (z<pi) and (z>pi/2) then
begin
y:=1.2-4*Sin(z);
end
else
If abs(z)<1 then
begin
y:=ln(1.8+z);
end
else
y:=z*exp((1/5)*ln(7.3-z));
V:=cos(0.2*(exp((1/3)*ln(y+3.6))))*exp(12.3-Abs(y)*ln(2));
Label3.Caption:=Label3.Caption+'. '+#9+format('%7.3f',[V])+#9+#9+'|'+'. '+#9+format('%7.3f',[z])+#13;
form1.lnsrsSeries3.AddXY(z,V);
z:=z+h;
until z>5
end;
end.