title: Numpy.dot TypeError: Cannot cast array data from dtype('float64') to dtype('S32') according to the rule 'safe'
body: <p>Why am I getting this error when using <code>np.dot(a,b.T)</code>:</p>
  
  <pre><code>TypeError: Cannot cast array data from dtype('float64') 
                 to dtype('S32') according to the rule 'safe'
  </code></pre>
  
  <p>a and b are of type <code>numpy.ndarray</code>. My <code>NumPy</code> version is 1.11.0.</p>