matrix repetition on diagonal

Hi, I have a matrix

T =
   1     0
   1     1

and i want to generate this matrix

T =
   1     0     0     0
   1     1     0     0
   0     1     1     0
   0     0     1     1

please note that T is not exactly repeating at diagonal. Can anyone help me with this ? thank you

Answer 1

[Andrei Bobrov]

T = [1,0;1,1];
N = 4;

[~,d] = spdiags(T);
out = full(spdiags(ones(N,numel(d)),d,N,N));

or

out = triu(tril(ones(N),sum(T(1,:))-1),1-sum(T(:,1)));

[Image Analyst]

More general than my method. Because he didn't give any rules, I was going to just give the very simple and straightforward (but snarky) answer of

T = [...
   1     0     0     0
   1     1     0     0
   0     1     1     0
   0     0     1     1]

[Stephen23]

@Image Analyst: nice. It fits the given explanation perfectly :)

Answer 2

[Stephen23]

I suspect you might want something like this:

>> T = [1,0;1,1];
>> N = 4;
>> R = zeros(1,N);
>> C = zeros(1,N);
>> R(1:size(T,1)) = T(:,1);
>> C(1:size(T,2)) = T(1,:);
>> toeplitz(R,C)
ans =
   1   0   0   0
   1   1   0   0
   0   1   1   0
   0   0   1   1
>>

but without a clear explanation of the algorithm that generates the output matrix from the input matrix, this is just a guess.

[Shajeel Iqbal]

Yes that's what i want. thank you

[Andrei Bobrov]

+1. Very good method!

Answer 3

[KSSV]

T = ones(4,1) ;
K = diag(T)+diag(T(1:end-1),-1)