title: "Error in port widths or dimensions" while producting 1x3 and 3x3 matrices
body: <p>The Matlab function named <code>C</code> generates a matrix with 3x3 dimension. I have to product it with the vector 1x3 made with the mux of sources <code>n_x</code>, <code>n_y</code>, <code>n_z</code>.</p>
  
  <p><a href="https://i.stack.imgur.com/XckEt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XckEt.png" alt="enter image description here"></a></p>
  
  <p>However, running this model causes two errors:</p>
  
  <blockquote>
    <p>Error in port widths or dimensions. Invalid dimension has been
    specified for input port 2 of 'untitled/Product'. </p>
    
    <p>Error in port widths or dimensions. Output port 1 of 'untitled/C' is a
    [3x3] matrix.</p>
  </blockquote>
  
  <p>Could you please explain me what's wrong with it?</p>