title: More than one exogenous input in NARX network in MATLAB
body: <p>In MATLAB, we can define a NARX network by the function:</p>
  
  <pre><code>net = narxnet(1:2,1:2,10);
  </code></pre>
  
  <p>and the network looks like:
  <a href="https://i.stack.imgur.com/2TJ4u.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2TJ4u.png" alt="enter image description here"></a></p>
  
  <p>The first <code>1:2</code> is the number of delay of <code>X</code> and the second <code>1:2</code> is the number of delay of <code>Y</code>. If I have another <code>Z</code> with the number of delay is <code>1:2</code> as well to be considered in the network, how should add it? </p>
  
  <p>I tried by the code</p>
  
  <pre><code>net.numInputs = 3;
  net.inputs{3}.name = 'Z';
  </code></pre>
  
  <p>then I have 
  <a href="https://i.stack.imgur.com/TobFw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TobFw.png" alt="enter image description here"></a></p>
  
  <p>Now, I want to change the number of delay of <code>Z</code> in the network,</p>
  
  <p>I tried </p>
  
  <pre><code>net.inputs{3}.feedbackOutput = 1:2;
  </code></pre>
  
  <p>then it returns</p>
  
  <pre><code>"net.inputs{i}.feedbackOutput" is a read only property."
  </code></pre>
  
  <p>how should I do to add the number of delay of <code>z</code> in the network. PS: I know how to connect <code>z</code> to the hidden layer.</p>