Selecting four elements then starting again.

Check the following code. I am not sure that is what you need, but it performs what you said in my understanding.

A = linspace(0,3,4);

Nth = 6;

for i=1:fix(Nth/4)
    for i=1:length(A)
        disp(A(i));
        pause(0.5)
    end
end

for i=1:mod(Nth,4)
    disp(A(i));
    pause(0.5)
end