title: what is the meaning of the return values of the scipy.cluster.hierarchy.linkage?
body: <p>Let assume that we have X matrix as follows:</p>
  
  <pre><code>[[9 0]
  [1 4]
  [2 3]
  [8 5]]
  </code></pre>
  
  <p>Then,</p>
  
  <pre><code>from scipy.cluster.hierarchy import linkage
  Z = linkage(X, method="ward")
  print(Z)
  </code></pre>
  
  <p>The returning matrix is follows:</p>
  
  <pre><code>[[  1.           2.           1.41421356   2.        ]
   [  0.           3.           5.09901951   2.        ]
   [  4.           5.          10.           4.        ]]
  </code></pre>
  
  <p>What is the meaning of the returning values?</p>