Metode Regula Falsi pada pascal

uses crt;

label ulang;

var

x1,x2,x3,y1,y2,y3 : real;

i : integer;

Ab : char;

data1 : real;

begin

ulang:

clrscr;

writeln('Tentukan nilai akar dari persamaan f(x)=x^3+x^2-3x-3 = 0 dengan metode regulafalsi');

write('Masukkan nilai x1 : ');readln(x1);

y1:=x1*x1*x1+x1*x1-3*x1-3;

writeln('Nilai f(x1) = ',y1:0:4);

repeat

begin

write('Masukkan nilai x2 : ');readln(x2);

y2:=x2*x2*x2+x2*x2-3*x2-3;

writeln('Nilai f(x2) = ',y2:0:4);

end;

if (y1*y2)<0 then

writeln('Syarat Nilai OK')

else

writeln('Nilai x2 belum sesuai');

until (y1*y2)<0;

writeln;

writeln('Penyelesaian persamaan karakteristik dengan metode regula falsi');

writeln('===========================================');

writeln(' n         x                 f(x)              error ');

writeln('===========================================');

repeat

begin

i:= i+1; x3 :=(x2-(y2/(y2-y1))*(x2-x1));

y3 := x3*x3*x3+x3*x3-3*x3-3;

if i <10  then

writeln(' ',i,'::',x3,'::',y3,'::',abs(y3),'::')

else

writeln(i,'::',x3,'::',y3,'::',abs(y3),'::');

if (y1*y3)<0 then

begin

x2 := x3;y2:=y3;

end

else

begin

x1:=x3;y1:=y3;

end;

end;

until abs(y3)<1E-07;

writeln('===========================================');

writeln('Akar persamaannya = ',x3);

writeln('errornya = ',abs(y3));

writeln('===========================================');

write('Apakah anda ingin mengulangi (y/t): ');

readln(Ab);

if (Ab='y') or (Ab='Y') then

begin

goto ulang;

end

else

end.