How to create this specified matrix?

Hi all. I have some values from U(1)...to...U(500) , and I need help to create this matrix:

Answer 1

[Stephen23]

One fast and easy way is to use toeplitz, it only needs one line of code:

>> U = 1:9;
>> toeplitz(U,[U(1),zeros(1,numel(U)-1)])
ans =
     1     0     0     0     0     0     0     0     0
     2     1     0     0     0     0     0     0     0
     3     2     1     0     0     0     0     0     0
     4     3     2     1     0     0     0     0     0
     5     4     3     2     1     0     0     0     0
     6     5     4     3     2     1     0     0     0
     7     6     5     4     3     2     1     0     0
     8     7     6     5     4     3     2     1     0
     9     8     7     6     5     4     3     2     1

or

tril(toeplitz(U))

Answer 2

[Azzi Abdelmalek]

u=1:10
n=numel(u)
v=repmat(u',1,n)
w=cell2mat(arrayfun(@(x) circshift(v(:,x),[x-1 0]),1:n,'un',0) )
out=tril(w)

Answer 3

[Andrei Bobrov]

   tril(toeplitz(u))