while 1
    A=zeros(3);                 % A=zeros(4);             
    sl_br=round(8*rand+1);      % sl_br=round(15*rand+1);
    A(sl_br)=1;
    [x y]=find(A==1);
    eukl_dist=sqrt(abs(x-1).^2+abs(y-1).^2);
    cityblock_dist=abs(x-1)+abs(y-1);
    
    iptsetpref('imviewinitialmagnification',100) %,'InitialMagnification','fit')
    imshow(A)
    pause(0.1)
end