Gauss-Siedel Method

I'm trying to switch my Jacobi method to Gauss-Siedel, but I'm struggling to fix it right now. Could I have some help please?

format long;
A = [9 1 1;
    2 10 3;
    3 4 11];
b = [10;
    19;
    0];
x = [0;
    0;
    0];
%z = [0,x'];
%for k=1:10
  %x = A*x + b;
  %z = [k,x'];
%end

%pause
x1 = 0.0; x2 = 0.0; x3 = 0.0;
z = [0,x1, x2, x3];
for k=1:30
   y1 = (1/9)*(-x2-x3+ 10);
   y2 = (1/10)*(-2*x1 -3*x3 +19);
   y3 = (1/11)*(-3*x1 -4*x2);
   x1 = y1; x2 = y2; x3 = y3;
    z = [k,x1,x2,x3];

end
fprintf('Number of Iterations: %d \n', k);
fprintf('x1: %f \n', x1);
fprintf('x2: %f \n', x2);
fprintf('x3: %f \n', x3);

[Geoff Hayes]

Chris - please describe what the problem is. Are you observing any errors and, if so, what are they?