CButter:

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   Build a continuous Butterworth Filter with output of the form
   
   dx/dt = ax + bu
       y = cx + du

   If no outputs are specified it will plot the frequency response 
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   Form:
   [a, b, c, d] = CButter( n, wC, tSamp, sType )
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   ------
   Inputs
   ------
   n             (1,1) Order
   wC            (1,1) Cutoff
   tSamp         (1,1)  Sampling frequency
   sType         (1,:) State equation type ('Delta' or 'Z')

   -------
   Outputs
   -------
   a                   State transition matrix
   b                   Input matrix
   c                   Measurement matrix
   d                   Feedthrough matrix

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Children:

Common: Control/C2DZOH
Common: Control/C2DelZOH
Common: Control/FResp
Common: Control/Series