title: Deprecation status of the NumPy matrix class
body: <p>What is the status of the <code>matrix</code> class in NumPy?</p>
  
  <p>I keep being told that I should use the <code>ndarray</code> class instead. Is it worth/safe using the <code>matrix</code> class in new code I write? I don't understand why I should use <code>ndarray</code>s instead.</p>