The bit you should have explained better is the construction rule of your matrix. The way I understand it, for numbers that are repeated, create a row in your matrix for each repeat where:
- first occurence occuring on row fi is marked 1 in column fi
- row ri of subsequent occurences are marked -1 in column ri
This may work for this:
nodes = [1; 1; 1; 2; 2; 2; 3];
pipes = 1:numel(nodes);
B0 = [];
[uniq, pos] = unique(nodes);
for node = uniq'
nodepipes = pipes(nodes == node);
if numel(nodepipes) > 1
pipeout = nodepipes(1);
for pipein = nodepipes(2:end)
Brow = zeros(1, numel(nodes));
Brow(pipeout) = 1;
Brow(pipein) = -1;
B0(end + 1, :) = Brow;
end
end
end
