Метод простой итерации - найти ошибки в коде

Program zadacha1;
type
matriza= array[1..20,1..20] of real;
Var b,prob,x,x1: array[1..20] of real;
i,j:real;
e:real;
n:integer;
Procedure vvod(var n:integer;var E:real; i,j:integer;var b:array of real;var a:matriza);
begin
Write('vvedite razmer matritci n');
Readln(n);
For i:=1 to n do
For j:=1 to n do begin
Write('A[',i,',',j,']=');
Readln(A[i,j]);
end;
For i:=1 to n do
If a[i,i]=0 then begin
Writeln('oshibka vvoda');
end;
For i:=1 to n do begin
Write('b[',i,']=');
Readln(b[i]);
end;
Write('vvedite tochnost E=');
Readln(E);
end;
Function otv(i,j:integer; var b,x,x1:array of real;a:matriza):real;
begin
For i:=1 to n do
begin
For i:=1 to n do
begin
If i=j then
a[i,j]:=-a[i,j]/a[i,i];
end;
b[i]:=b[i]/a[i,i];
a[i,i]:=0;
end;
For i:=1 to n do
begin
For j:=1 to n do
Write(a[i,j]:4:2,'');
Write(b[i]:4:2,'');
end;
For i:=1 to n do
x[i]:=0;
repeat
For i:=1 to n do
begin
For j:=1 to n do
x1[i]:=x1[i]+a[i,j]*x[j];
x1[i]:=x1[i]+b[i];
end;
For i:=1 to n do
begin
x[i]:=x1[i];
x1[i]:=0;
end;
until abs(x1[i]-x[i])<E;
otv:=x[i];
end;
 
Procedure vivod(i,n:integer;var otv:array of real);
begin
For i:=1 to n do
Writeln(otv[i]);
end;
begin
vvod(n,a,b);
otv(i,j,b);
vivod(otv[i]);
end.