How to concatenate smaller matrices to form a larger matrix? - matlab

Question

I would like to concatenate 14641 number of 3X3 matrices into a matrix of size 363X363 and the large matrix must contain 121 submatrices in each row(121*3=363 columns) and 121 such rows of submatrices(121*3=363rows).I have gone through the similar questions but I didn't get the correct logic to concatenate large number of matrices.
Awaiting your suggestions. Thanks in advance.
PS: I got those 3X3 matrices from a 363X363 matrix. The following code is for splitting the single matrix into submatrices.
I=imread('photo.jpg');
B = randi([0 255],363,726,3);
B(1:numel(I)) = I;
L=B(1:363,1:363);
[al,bl]=size(L);
ImageSize=al*bl;
BlockD=3; % i assume 3x3 block
BlockSize=BlockD*BlockD;
TotalBlocks=ImageSize/BlockSize;
subL=zeros(BlockD,BlockD,TotalBlocks); %arrays of blocks.
LL=double(L);
k=1;
for i=1:BlockD:al
for j=1:BlockD:bl
subL(:,:,k)=LL(i:i+BlockD-1,j:j+BlockD-1);
k=k+1;
end
end
Now I want to concatenate all these 'subL' submatrices to form 'LL' again
Using blocproc instead of above code
I tried using blockproc function instead of the above code. I did this piece of code and is working pretty well.Thank you
I=imread('photo.jpg');
B = randi([0 255],363,726,3);
B(1:numel(I)) = I;
L=B(1:363,1:363);
q=[1 2 3 4];
fun=#(block_struct)quaternionrotate(q,block_struct.data);
LL = blockproc(L,[3 3],fun);
and the function quaternionrotate is
function [ Lrot1 ] = quaternionrotate(q,A)
qinv=quatinv(q);
B=zeros(3,1);
A1=[B A];
Lrot=quatmultiply(q,quatmultiply(A1,qinv));
Lrot(:,1)=[];
Lrot1=Lrot;
end

Answer 1

Finally figured this out!
% I used this to make 14641 3x3 sample matrices, you should use your own
matrix = ones(3,3);
for i = 2:14641
matrix = [matrix, i*ones(3,3)];
end
c_size = 121;
output = cell(c_size, c_size) % Make 121x121 cell matrix
% Populate the cell matrix
for i = 1:1:c_size
for j = 1:1:c_size
output(i,j) = {matrix(1:3, (i-1)*c_size*3+(j-1)*3+1 : (i-1)*c_size*3+(j-1)*3+3)};
end
end
This breaks up the 43923x3 size matrix of 363 3x3 matrices into a 121x121 cell matrix of 3x3 matrices. Now that's a tongue twister...
Either way the code does what you need! :)