def vecDistanceSquared(inPtA, inPtB):
  """calculate the square of the distance between two points"""
  ddx = inPtA[0] - inPtB[0]
  ddy = inPtA[1] - inPtB[1]
  ddz = inPtA[2] - inPtB[2]
  return ddx*ddx + ddy*ddy + ddz*ddz