StateSensor:

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   State sensor. Gives the ideal states of the system.

   Since version 7.
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   Form:
   y = StateSensor( action, d, k )
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   Inputs
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   action      (1,:)     'initialize', 'derivative', 'output', 'fail' 
   d           (1,1)     Depends on the action
   k           (1,1)     Unique Spacecraft Indentifier

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   Outputs
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   y           (1,1)     Depends on the action

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