title: Loading vs linking in Cython modules
body: <p>While exploring Cython compile steps, I found I need to link C libraries like math explicitly in setup.py. However, such step was not needed for numpy. Why so? Is numpy being imported through usual python import mechanism? If that is the case, we need not explicitly link <em>any</em> extension module in Cython?</p>
  
  <p>I tried to rummage through the official documentation, but unfortunately there was no explanation as to when an explicit linking is required and when it will be dealt automatically.</p>