Notch:

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   Creates a second order transfer function.
   	
   Creates a second order transfer function to produce
   a large + or - gain at frequency wc.

          s^2/wc^2 + 2 zzs/wc + 1
   K(s) = ------------------------
          s^2/wc^2 + 2 zps/wc + 1

   For a bandpass with infinite gain at wc enter inf for Kdb. For a
   notch with zero gain at wc enter NaN. Any argument for nmp
   will make the filter nonminimum phase.

   Since version 1.
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   Form:
   [a, b, c, d] = Notch( Kdb, wc, dw, fType, tSamp, sType )
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   ------
   Inputs
   ------
   Kdb                  Peak gain (db)
   wc                   Notch frequency (rad/sec)
   dw                   Half notch width (rad/sec)
   fType                'nmp' means nonminimum phase notch, 'mp'
                        is minimum phase
   tSamp                Sampling frequency
   sType                State equation type ('Delta' or 'Z')

   -------
   Outputs
   -------
   a                    Plant matrix
   b                    Input matrix
   c                    Measurement matrix
   d                    Feedthrough matrix

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	References:	Wie, B., K. Byun, "New Generalized Structural Filtering
               Concept for Active Vibration Control Synthesis,"
               J. Guidance and Control, Vol. 12, No. 2, March-April 1989,
               pp. 147-154.
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Children:

Common: Control/C2DZOH
Common: Control/C2DelZOH
Common: Control/FResp
Common: Control/ND2SS