Attempting to randomly present a set of stimuli

Hi all,

I am currently trying to randomly present a set of stimuli. The stimuli set is 21 images; each image is a different consonant from the alphabet. This stimuli are required to be presented randomly in a loop such that there will be 48 image presentations in one trial.

Although my following code is basic, I have managed to load in the images and get them to be presented one after each other with an interval of .9 seconds between each image.

clear all
imgs=cell(21,1);
imgs{1}= imread('image_1.jpg');
imgs{3}= imread('image_2.jpg');
imgs{2}= imread('image_2.jpg');
imgs{3}= imread('image_3.jpg');
imgs{4}= imread('image_4.jpg');
imgs{5}= imread('image_5.jpg');
imgs{6}= imread('image_6.jpg');
imgs{7}= imread('image_7.jpg');
imgs{8}= imread('image_8.jpg');
imgs{9}= imread('image_9.jpg');
imgs{10}= imread('image_10.jpg');
imgs{11}= imread('image_11.jpg');
imgs{12}= imread('image_12.jpg');
imgs{13}= imread('image_13.jpg');
imgs{14}= imread('image_14.jpg');
imgs{15}= imread('image_15.jpg');
imgs{16}= imread('image_16.jpg');
imgs{17}= imread('image_17.jpg');
imgs{18}= imread('image_18.jpg');
imgs{19}= imread('image_19.jpg');
imgs{20}= imread('image_20.jpg');
imgs{21}= imread('image_21.jpg');

figure;
for idx = 1:length(imgs)
    A = imshow(imgs{idx});
    pause(.9)
    delete(A)
end

This code produces 21 image presentations, one after each other. Does anyone have any ideas of how I can manipulate this code to ensure that I get 48 image presentations, instead of being limited to 21?

I appreaciate any help and guidance anyone can lend me.

Thank you.