Q2AU:

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   Convert a quaternion to an angle and a unit vector. 
   If q = [1;0;0;0] then u is set to [1;0;0].

   Since version 2.
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   Form:
   [angle, u] = Q2AU( q )
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   ------
   Inputs
   ------
   q       (4,1)   Quaternion

   -------
   Outputs
   -------
   angle   (1,1)   Angle
   u       (3,1)   Unit vector

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Children:

Math: Linear/Mag
Math: Linear/Unit