here is an example:
a = [1 2 3]';
b = [1 2]';
c = [1 2 3 4 5 6 7]';
sets = {a,b,c}; % let a, b, and c be your column sets. Store them in an array 'sets'
max_size = 0;
%figure out the maximum size
for i = 1:numel(sets)
if size(sets{i},1) > max_size
max_size = size(sets{i},1); % set max size, if current column is greater than the current max size
end
end
% append zeros if smaller than the max size
for i = 1:numel(sets)
if size(sets{i},1) < max_size
sets{i} = vertcat(sets{i},zeros(max_size-size(sets{i},1),1));
end
end
sets = cell2mat(sets) %concatenate into a matrix
