title: The name of this type of matrix
body: <p>whats the name and the rules of a matrix thats like this.</p>
  
  <pre><code>    1   2   3   4   5   6
  1   X   .   .   .   X   .
  2   .   .   .   X   .   .
  3   .   .   .   .   X   .
  4   .   .   .   .   .   .
  5   .   .   .   .   X   .
  6   X   .   .   .   .   X
  </code></pre>
  
  <p>and it gets turned into this.</p>
  
  <pre><code>    1   2   3   4   5   6
  1   1   1   1   1   2   2
  2   1   1   1   2   3   3
  3   1   1   1   2   4   4
  4   1   1   1   2   4   4
  5   1   1   1   2   5   5
  6   2   2   2   3   6   7
  </code></pre>