Getting B+ matrix (Warshall algorithm) in Matlab Pseudocode:


// B = nxn binary matrix
// Bm = resulting matrix
for (i=1; i&lt;=n; i++)
{
  for (j=1; j&lt;=n; j++)
  {
    if (B[i,j] == 1)
    {
      for (k=1; k&lt;=n; k++)
      {
        Bm[i,j] = B[i,j] | B[k,j];
      }
    }
  }
}



This is the Warshall algorithm written (in my way):

B = [1 1 0 0 0; 0 0 0 1 0; 0 0 0 0 1; 0 1 0 0 0; 0 0 0 0 0];

n = 5;

Bm = zeros(n);

for i = 1:n
    for j = 1:n
        if B(i,j) == 1
            for k = 1:n
                Bm(i,k) = B(i,k) | B(k,j);
            end
        end
    end
end


It works but, how can I improve the matrix loops?
This post may help you in removing a loop:
http://mathforum.org/kb/message.jspa?messageID=845980

Furthermore, one way to speed up your code is to use a short circuit logical operator:

B(i,k) || B(k,j); 


Also it seems to have a small effect if you use a logical matrix as input rather than a double:

B = logical(b);


Last and least, it would be nicer to initialize Bm with the datatype that it will have:

Bm = false(n)