title: What's state_size of a MultiRNNCell in TensorFlow?
body: <p>With the config as below for a <code>BasicLSTM</code> cell:</p>
  
  <pre><code>...
  num_layers = 2 
  num_steps = 10 
  hidden_size = 200    
  ...
  </code></pre>
  
  <p>I use 2-hidden layers model:</p>
  
  <pre><code>lstm_cell = rnn_cell.BasicLSTMCell(hidden_size, forget_bias=0.0) 
  cell = rnn_cell.MultiRNNCell([lstm_cell] * 2)
  </code></pre>
  
  <p>What is the <code>cell.state_size</code>?</p>
  
  <p>I got it as 30 x 800, but I can't understand how it comes to?</p>
  
  <p>PS: refer to the source code in <a href="https://github.com/tensorflow/tensorflow/blob/97f585d506cccc57dc98f234f4d5fcd824dd3c03/tensorflow/python/ops/rnn_cell.py#L353" rel="nofollow noreferrer">https://github.com/tensorflow/tensorflow/blob/97f585d506cccc57dc98f234f4d5fcd824dd3c03/tensorflow/python/ops/rnn_cell.py#L353</a></p>
  
  <p>It seems to return <code>statesize</code> as <code>2 * unitsize</code>. But why should the state size be twice of the unit size?</p>