Maintain colors when ploting during a loop using hold on.

Hey, so imtrying to plot 5 lines where each line new value (5 new 'y' axes values) are being calculated iterativly using a loop. I want to add every iteration the new 5 values while to the same exsiting 5 lines with their colors maintaind. Thus keeping a constant color for 5 lines. I have written something like this:

figure(1);
hold on;
while (max(abs(dif)) > 1*10^-6)
   if (mod(iteration_num,100) == 0)
     plot(repmat(iteration_num,1,size),Xr(1:size));   
   end
   iteration_num = iteration_num + 1;
   Xr(r) = Xr(r) + k*((1/Xr(r)^alpha) - help);
end

but every time I get inside the loop the plot uses 5 new colors for the new values while I want it to be consistent Can anyone help me please? Thanks

[dpb]

See the section on Animation in the Graphics help; particularly you may find joy in the animatedline animal...