title: Multiplexer with variable size signals
body: <p>I am using MATLAB/simulink 2014a and I would like to feed a multiplexer (with 3 ports) with 3 signals which have variable-sizes. But I get the error:</p>
  
  <p><img src="https://i.stack.imgur.com/JaTl8.png" alt="enter image description here"></p>
  
  <p>Someone could help me to solve the problem? </p>
  
  <p>Thanks a lot.</p>