Why does tensorlow LSTM takes only the hidden size as input?
<p>In the tensorflow <a href="https://www.tensorflow.org/versions/r0.9/api_docs/python/rnn_cell.html#LSTMCell" rel="nofollow">LSTM</a> cell we only initialize it by number of units (<code>num_units</code>) which is the hidden size of the cell. However, the cell should also take an input <code>x</code>. And since the underlying operation is a matrix multiplication operation the size of <code>x</code> should also play a role in setting up the LSTM weight. So, shouldn't the cell take the size of the input <code>x</code> also as an initialization parameter? </p>

<p>LSTM cell (or other types of RNN cells) is just an object you pass to the function such as <code>tf.nn.rnn</code>. <code>tf.nn.rnn</code> takes cell and data for input.  Cell is called inside of rnn function with the data you've passed to <code>tf.nn.rnn</code>. </p>

python tensorflow lstm