Vectorize nested for loop with matrix indexing

Hello everyone, the code shown below works as intended. It's just that it takes quite a bit of time to execute.

Note : T is a 512x3 array of doubles, Z1 is a 512x512 array of doubles and Z1_encrypt = Z1 OR T

Z1_encrypt = [];
Z2_encrypt = [];
Z3_encrypt = [];
for i = 1:1:512
    disp(i)
    for j = 1:1:512
        Z1_encrypt = [Z1_encrypt bitor(Z1(j,i),T(j,1),'uint64')];
        Z2_encrypt = [Z2_encrypt bitor(Z2(j,i),T(j,2),'uint64')];
        Z3_encrypt = [Z3_encrypt bitor(Z3(j,i),T(j,3),'uint64')];
    end
end

I was looking into vectorization of code to speed it up and went over quite a few examples. One very similar example can be found here, but it was of not much help to me.

It would be great if someone could help me out here.

Answer 1

[Chunru]

% The following code is slow, because the array size is growing.  Memory
% allocation will slow down the program

% Z1_encrypt = [];
% Z2_encrypt = [];
% Z3_encrypt = [];
% for i = 1:1:512
%     disp(i)
%     for j = 1:1:512
%         Z1_encrypt = [Z1_encrypt bitor(Z1(j,i),T(j,1),'uint64')];
%         Z2_encrypt = [Z2_encrypt bitor(Z2(j,i),T(j,2),'uint64')];
%         Z3_encrypt = [Z3_encrypt bitor(Z3(j,i),T(j,3),'uint64')];
%     end
% end

% ry the following for speed
Z1_encrypt = bitor(Z1,T(:,1),'uint64');
Z2_encrypt = bitor(Z1,T(:,2),'uint64');
Z3_encrypt = bitor(Z1,T(:,3),'uint64');

[Divye Kalra]

This worked, thanks!