Program Membuat Metode Tabulasi (dengan PASCAL)

uses crt;
label ulang;
var x,x1,x2,xa,xb,xc,y,y1,y2,ya,yb:real;
i,j,k:integer;
ab:char;
begin ulang;
clrscr;
writeln('Tentukan akar Penyelesaian dengan Metode Tabulasi dari f(x)=x^3-7x++1');
writeln;
write('Input Nilai x1=');
readln(x1); y1:=x1*x1*x1-7*X1+1;
writeln('f('x1:0:2,')=',y1:0:4);
repeat begin write('Masukan nilai x2=');
readln(x2); y2:=x2*x2*x2-7*x2+1;
writeln('f('x2:0:2,')=',y2:0:4);
writeln;
writeln('Syarat(x1*x2) < 0'); write(x1*x2='y1*y2:0:5); if (y1*y2) < 0 then write ('Nilai OK') else write('Nilai tidak sesuai'); readln; end; until (y1*y2) < 0; clrscr; k:=0; repeat begin k:=k+1; if x1 > x2 then
begin
xa:=x1;
xb:=x2;
end
else
begin
xa:=x2;
xb:=x1;
end;
xc:=(xa-xb)/10;
i:=0;
repeat
begin
i:=i + 1;
x:=xb+xc+i;
ya:=x*x*x-7*x+1;
yb:=(x-xc)*(x-xc)*(x-xc)-7*(x-xc)+1;
end;
until(ya*yb) < 0;
x1:=x;
x2:=x-xc;
writeln('Tabulasi ke-'.k);
writeln('--------------------');
writeln(n x f(x) error ');
writeln('--------------------');
for j:=1 to 9 do
begin
x:=xb+xc*(j-1);
y:=x*x*x-7*x+1;
writeln('',j,'::',x,'::',y,'::',abs(y),'::');
end;
for j:=10 to 11 do
begin
x:=xb+xc*(j-1);
y:=x*x*x-7*x+1;
writeln('',j,'::',x,'::',y,'::,abs(y),'::');
end;
writeln('------------------------');
end;
readln;
until abs(y) < 10e - 8;
writeln('Akar pendekatan nya adalah x=',x);
writeln('Error =',abs(y));
writeln;
write('Apakah anda ingin mengulangi?(Y/T):');
readln(ab);
if (ab='Y') or (ab='y') then
begin
goto ulang;
end
end.