clear %Clears everything
clc %Clears the screen

x = 2; %x == 2

stop = 10^(-15); % stop == 0.0000000000000001

while( x > stop) %While x is of greater value than stop
    x = x / 2; %Divide x by two.
    
    %So in the first pass x == 1
    %   in the second pass x == 1/2
    %... and it goes on
    %... an on
    %as long as x is greater than stop...
    
    %If you do not program your stuff correctly...
    %It may never stop !
end

x