Метод Гаусса для решения СЛАУ

Program MetodGaussa;
Uses Crt;
Var
  a,a1: array[1..10, 1..10] of real;
  b,b1: array[1..10] of real;
  x: array[1..10] of real;
  n, i, j, k: integer;
  r, g: real;
  
function EnterMatrix(n : Integer): real;
begin
  clrscr;
  writeln('Vvedite koef sistemi i sv chleni');
  for i := 1 to n do
  begin
    for j := 1 to n do
    begin
      write('a[', i, ',', j, ']= ');
      readln(a[i, j]);
      a1[i,j]:=a[i,j];
    end;
    Write('b[', i, ']= ');
    readln(b[i]);
end;
end;
 
function ShowMatrix(n :Integer): real;
begin
  clrscr;
  WriteLn('Matrica A:');
  for i := 1 to n do
  begin
    for j := 1 to n do
    begin
      write('  ',a1[i,j]);
      if j = n then
      writeln
    end;
  end;
  WriteLn('Matrica B:');
  for i := 1 to n do
    writeln('  ', b[i]);
readln;
end;
 
 
function Metod:real;
begin
  for k := 1 to n do { прямой ход }
  begin
    for j := k + 1 to n do
    begin
      r := a[j, k] / a[k, k];
      for i := k to n do
      begin
        a[j, i] := a[j, i] - r * a[k, i];
      end;
      b[j] := b[j] - r * b[k];
    end;
  end;
  for k := n downto 1 do { обратный ход}
  begin
    r := 0;
    for j := k + 1 to n do
    begin
      g := a[k, j] * x[j];
      r := r + g;
    end;
    x[k] := (b[k] - r) / a[k, k];
  end;
  writeln('Korni:');
  for i := 1 to n do
    write('x[', i, ']=', x[i]:0:4, '   ');
    readln;
end;
 
function Check:real;
begin
  clrscr;
  writeln('Proverka v sootvetstvii s matricey B: ');
  for i:=1 to n do
   begin
    for j:=1 to n do
      b1[i]:=b1[i]+a1[i,j]*x[j];
     writeln(b1[i]:4:4,' ');
    end;
  readln;
end;
 
Begin
  WriteLn('Poryadok matrici: ');
  Readln(n);
  EnterMatrix(n);
  ShowMatrix(n);
  Metod;
  Check;
  Readln;
END.

for k := n downto 1 do { обратный ход}
  begin
    r := 0;
    for j := k + 1 to n do
    begin
      g := a[k, j] * x[j];
      r := r + g;
    end;
    x[k] := (b[k] - r) / a[k, k];
  end;