title: What might be the cause of 'invalid value encountered in less_equal' in numpy
body: <p>I experienced a RuntimeWarning </p>
  
  <pre><code> RuntimeWarning: invalid value encountered in less_equal
  </code></pre>
  
  <p>Generated by this line of code of mine:</p>
  
  <pre><code>center_dists[j] &lt;= center_dists[i]
  </code></pre>
  
  <p>Both <code>center_dists[j]</code> and <code>center_dists[i]</code> are numpy arrays</p>
  
  <p>What might be the cause of this warning ?</p>