Repeat calculation 24 times (Cell arrays)

I have to repeat a calculation 24 times and store the results. I have written the code for the first column. How do I repeat it 24 times for each column.

p=[0.1,0.5,1,2.5,5,10,25,50,75,90,95,97.5,99,99.5,99.9];
for i=1:50
    for j=1:500000
        stress(j,i)=E(i,1)*D(j,1);
    end
end
for k=1:15
    for i=1:50;
        Stressperc(k,i)=prctile(stress(:,i),p(1,k));
    end
end

[Walter Roberson]

Note that more efficient would be

p=[0.1,0.5,1,2.5,5,10,25,50,75,90,95,97.5,99,99.5,99.9];
for i=1:50
   stress(:,i) = E(i,1) .* D(:,1); 
end
Stressperc = prctile(stress, p);

Answer 1

[Walter Roberson]

p=[0.1,0.5,1,2.5,5,10,25,50,75,90,95,97.5,99,99.5,99.9];
Stressperc = zeros(numel(p), 50, 24);

for col = 1 : 24
    for i=1:50
       stress(:,i) = E(i,1) .* D(:,col); 
    end
    Stressperc(:,:,col) = prctile(stress, p);
end