Plotting combaine stream function

Hi;

Please, I have two matrix R(100*1) and Y(100*1). I used below code to plot stream function and its work properly. I got 100 plots.However, I have a more difficult situation. Now I am trying to combine stream function. I mean I have 100 steps to plot this mean I will have 100 plots.One plot for each step. My new case is combining stream function after each 5 steps.

This mean from step 1-5 the plots it will be the same but for step 6 the stream function will be stream function in step 1 plus stream function in step 6, For step 7 it will be step 2 plus step 7 and so on until I reach step 11 which will be stream function for step 1+6+11. and so on. I have to add stream function for every 5 steps.

Stream function from step 1-5 same as old stream function

Stream function from step 6-10 will be

Stream function from step 6 will be step 1 from old stream function+step 6 from old stream function

Stream function from step 7 will be step 2 from old stream function+step 7 from old stream function and so on for next step until step 10

Stream function from step 11-15 will be

Stream function from step 11 will be step 1 from old stream function+step 6 from old stream function+step 11 from old stream function

Stream function from step 12 will be step 2 from old stream function+step 7 from old stream function+step 12 from old stream function and so on for next step until step 15

and so on until I reach step 100

I can accomplish that by making a 3D matrix (for one stream function) each slide will be stream function at one step and to get new combination stream function I will add these slides each 5 steps. For example, Stream function at step 6 will be slide 1+6 and for 11 will be 1+6+11 and so on but this will consume long time to get the result.

What is the best way to accomplish that?

 mkdir('MatLab')
pridir = 'MatLab';
for i=1:100
R= R1(i); 
Y= Y1(i);
figure('units','normalized','outerposition',[0 0 1 1])  
[r,y]= meshgrid(linspace(0,4),linspace(0,4));
k=((r*R)/((y-Y)^2+(r+R)^2));
U=exp(k-R.^2-Y.^2)
[~,h] = contour(r,y,U,[0.001 0.01 0.05 0.08 0.1  0.2 0.25 0.3 0.4]);
set(h,'ShowText','on','TextStep',get(h,'LevelStep')*2)
colormap cool
xlabel('r')                                               
ylabel('y')                                               
grid on
axis square
printto = sprintf('%s\\MatLab%03d',pridir,i);
print('-djpeg90',printto)
close(gcf);
end

Thank you.