Eul2Q:

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   Converts 3-2-1 Euler angles to a quaternion using the half angle
   formulas. 

   Since version 1.
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   Form:
   q = Eul2Q( e )
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   ------
   Inputs
   ------
   e		(3,:)    Euler angles (rad)

   -------
   Outputs
   -------
   q		(4,:)    Equivalent quaternion

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