title: How to convert a symmetric matrix into "dist" object?
body: <p>I want to use <code>hclust</code> to cluster a data. But I don't want to use "dist()" to generate the dist object. Then I found out that I cannot pass a symmetric matrix as distance matrix into <code>hclust</code>.</p>
  
  <p>How to convert a symetric matrix into "dist" object?</p>