The more that you set up before the loop, the neater and clearer the code will be:
mat = reshape(1:25,5,5).'; % input matrix, any size
%
blkR = 3; % output block rows
blkC = 3; % output block columns
stpR = 2; % step size rows
stpC = 1; % step size columns
%
inSz = size(mat);
vecR = blkR:stpR:inSz(1); % blocks' end rows
vecC = blkC:stpC:inSz(2); % blocks' end columns
%
numR = numel(vecR); % count blocks along rows
numC = numel(vecC); % count blocks along columns
out = cell(numR,numC);
for kR = 1:numR
for kC = 1:numC
idxR = vecR(kR)+(1:blkR)-blkR; % row indices
idxC = vecC(kC)+(1:blkC)-blkC; % column indices
out{kR,kC} = mat(idxR,idxC); % use indices
end
end
and checking the output:
>> out{:}
ans =
1 2 3
6 7 8
11 12 13
ans =
11 12 13
16 17 18
21 22 23
ans =
2 3 4
7 8 9
12 13 14
ans =
12 13 14
17 18 19
22 23 24
ans =
3 4 5
8 9 10
13 14 15
ans =
13 14 15
18 19 20
23 24 25
>>
