code: public static double orientationAngle(Point3d[] fixed, Point3d[] moved,
  			boolean centered) {
  		if (!centered) {
  			fixed = CalcPoint.clonePoint3dArray(fixed);
  			moved = CalcPoint.clonePoint3dArray(moved);
  			CalcPoint.center(fixed);
  			CalcPoint.center(moved);
  		}
  		return orientationAngle(fixed, moved);
  	}
docs: The angle of the relative orientation of the two sets of points in 3D.
  Equivalent to {@link #angle(Quat4d)} of the unit quaternion obtained by
  {@link #relativeOrientation(Point3d[], Point3d[])}.
  
  @param fixed
  array of Point3d. Original coordinates will not be modified.
  @param moved
  array of Point3d. Original coordinates will not be modified.
  @param centered
  true if the points are already centered at the origin
  @return the angle in radians of the relative orientation of the points,
  angle to rotate moved to bring it to the same orientation as
  fixed.