ef METHOD_NAME(self, pos):
  """Uses the minimum image convention to return a list of particles to the
     unit cell.
  Args:
     atom: An Atom object.
  Returns:
     An array giving the position of the image that is inside the
     system box.
  """
  s = depstrip(pos).copy()
  s.shape = (len(pos)/3,3)
  s = np.dot(depstrip(self.ih),s.T)
  s = s - np.round(s)
  s = np.dot(depstrip(self.h),s).T
  pos[:] = s.reshape((len(s)*3))