Mauch MIREX 2010

function M = unroll_higher_order_topology(intra, inter, T, intra1)

% UNROLL_DBN_TOPOLOGY Make the block diagonal adjacency matrix for a DBN consisting of T slices

% M = unroll_dbn_topology(intra, inter, T, intra1)

%

% intra is the connectivity within a slice, inter between two slices.

% M will have intra along the diagonal, and inter one above the diagonal.

% intra1 is an optional argumnet, in case the intra is different for the first slice.

if nargin < 4 

    intra1 = intra; 

end;

ss = length(intra); % slice size

M = sparse(ss*T, ss*T);

[rows,columns,order] = size(inter);

for t1 = 1:T

  b = 1 + (t1 - 1)*ss : t1*ss;

  if t1 == 1

      M(b,b) = intra1;

  else

      M(b,b) = intra;

  end

  for t2 = 1:order

    if t1 + t2 <= T

      M(b,b+t2*ss) = inter(:,:,t2);

    end

  end

end