code: def array_ratio_std(values_n, sigmas_n, values_d, sigmas_d):
      r
      std = np.sqrt((sigmas_n / values_n) ** 2 + (sigmas_d / values_d) ** 2)
      std *= (values_n / values_d)
      return std
docs: r"""Gives error on the ratio of 2 floats or 2 1-dimensional arrays given
      their values and uncertainties. This assumes the covariance = 0, and that
      the input uncertainties are small compared to the corresponding input
      values. _n and _d denote the numerator and denominator respectively.
  
      Parameters
      ----------
      values_n: float or numpy array
          Numerator values.
      sigmas_n: float or numpy array
          :math:`1\sigma` uncertainties on values_n.
      values_d: float or numpy array
          Denominator values.
      sigmas_d: float or numpy array
          :math:`1\sigma` uncertainties on values_d.
  
      Returns
      -------
      std: float or numpy array
          :math:`1\sigma` uncertainty on values_n / values_d.