function [A] = myMix(A);
  for i = 1 : 100
    [x y] = find(A==0);
    direction = ceil(4*rand);
      if (direction==1  && x~=1)   %hole up
          A(x,y)=A(x-1,y);
          A(x-1,y)=0;
      endif
      if (direction==2 && x~=3)    %hole down
          A(x,y)=A(x+1,y);
          A(x+1,y)=0;
      endif
      if (direction==3 && y~=1)    %hole left
          A(x,y)=A(x,y-1);
          A(x,y-1)=0;
      endif
      if (direction==4 && y~=3)     %hole right
          A(x,y)=A(x,y+1);
          A(x,y+1)=0;
      endif
##      A             % if we remove the comment each step of mixing
##      pause(0.1)    % will be shown with 0.1s pause between each state
  endfor
  %B = A;
endfunction