def getRatios(vect1, vect2):
  """
  Assumes: vect1 and vect2 are lists of equal length.

  Returns: a list containing ratios.
  """

  assert len(vect1) == len(vect2), "length of vect1 and vect2: not equal"

  ratios = []

  for num1, num2 in zip(vect1, vect2):
    try:
      ratios.append(num1/num2)
    except ZeroDivisionError:
      ratios.append(float("nan")) # Not a number
    except:
      raise ValueError("getRatios called with bad args")

  return ratios