Your code commented:
length = HW(:,1); %You're creating a length variable (which has nothing to do with length) which will shadow the length function.
for i = 1:size(HW(:,1)) %size(HW, 1) is more logical and faster
numbers(i) = unique(HW(i,1)); %HW(i, 1) is the first number in row i. unique is just going to return that number.
%in effect your loop is equivalent to:
%number = HW(:, 1);
%clearly not what you want to do
count(i) = hist(length(HW(:,i)),numbers(i)); %makes no sense at all
%either you're trying to index your length variable with HW(:, i) but why (and that'll only work if the numbers in the columns are all strictly positive integers smaller than size(HW, 1)
%or you're trying to use the length function (which will not work because of your length variable). again why?
%furthermore your i index works over the rows and your using it as a column index
end
A simple way of doing what you want would be just one call:
hist(HW.', unique(HW(:)); %transpose HW since hist works on columns not rows.
