code: def dcm(self):
          
          if self._dcm is None:
              if self._q is not None:
                  # try to get dcm from q
                  self._dcm = self._q_to_dcm(self.q)
              elif self._euler is not None:
                  # try to get get dcm from euler
                  self._dcm = self._euler_to_dcm(self._euler)
          return self._dcm
docs: Get the DCM
  
          :returns: 3x3 array