QError:

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   Small angle errors between two quaternions.
   This routine gives the correct sign when both vectors transform from 
   frame a to frame b and frame b is the body frame. If the convention is 
   reversed you must reverse the sign.
   To force the positive first element convention enter any 3rd argment.

   Since version 1.
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   Form:
   angle = QError( qRef, qMeas, pos )
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   ------
   Inputs
   ------
   qRef            (4,1)  Reference quaternion
   qMeas           (4,1)  Measured quaternion
   pos             (1,1)  If entered make the first element positive
   always

   -------
   Outputs
   -------
   angle           (3,1)  Vector of small angular errors (rad)

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Children:

Common: Quaternion/QMult
Common: Quaternion/QPose