Проверьте правильность кода

const
  n= 4;
  e= 0.001;
  a: array[1..n,1..n] of Real=((0.31,0.14,0.30,0.27),(0.26,0.32,0.18,0.24),(0.61,0.22,0.20,0.31),(0.40,0.34,0.36,0.17));
  b: array[1..n] of Real=(1.02,1.00,1.34,1.27);
 
var
  x: array[1..n,1..n] of real;
  i,j,p,k: byte;
  x1,x2,x3,x4,t1,t2,t3,t4:real;
 
begin
  writeln('система уравнений:');
  for i:=1 to n do begin
    for j:=1 to n do write(a[i,j]:4);
    writeln(b[i]:4);
  end;
     {проверка диаганалей}
  for i:=1 to n do begin
    p:=0;
    for j:=1 to n do
      if i<>j then p:=p+a[i,j];
    if a[i,i]<p then break;
  end;
     {перестановка строк}
  for i:=n downto 2 do begin
    for j:=1 to n do begin
      p:=a[i,j];
      a[i,j]:=a[i-1,j];
      a[i-1,j]:=p;
    end;
    p:=b[i];
    b[i]:=b[i-1];
    b[i-1]:=p
  end;
  for i:=1 to n do begin
    for j:=1 to n do write(a[i,j]:4);
    writeln(b[i]:4);
  end;
  writeln;
     {искл. диагоналей}
  for i:=1 to n do begin
    j:=1;
    k:=0;
    while (k<=n) and (j<=n) do
      if j<>i then begin
        inc(k);
        x[i,k]:=a[i,j]/-a[i,i];
        inc(j);
      end
      else inc(j);
    x[i,n]:=b[i]/a[i,i];
  end;
  for i:=1 to n do begin
    for j:=1 to n do write(x[i,j]:7:4);
    writeln;
  end;
  x1:=0;
  x2:=0;
  x3:=0;
  x4:=0;
  repeat
    t1:= x1;
    t2:= x2;
    t3:= x3;
    t4:= x4;
    x1:=x[1,1]*t2+x[1,2]*t3+x[1,3]*t4+x[1,4];
    x2:=x[2,1]*t1+x[2,2]*t3+x[2,3]*t4+x[2,4];
    x3:=x[3,1]*t1+x[3,2]*t2+x[3,3]*t4+x[3,4];
    x4:=x[4,1]*t1+x[4,2]*t2+x[4,3]*t4+x[4,4];
    writeln('x1=',x1:6:4,' x2=',x2:6:4,' x3=',x3:6:4,' x4=',x4:6:4);
  until (Abs(x1-t1)<=e) and (Abs(x2-t2)<=e) and (Abs(x3-t3)<=e) and (Abs(x4-t4)<=e);
  readln;
end.