code: def _distance_stats_sqr_fast_generic(x, y, dcov_function):
      
      covariance_xy_sqr = dcov_function(x, y)
      variance_x_sqr = dcov_function(x, x)
      variance_y_sqr = dcov_function(y, y)
      denominator_sqr_signed = variance_x_sqr * variance_y_sqr
      denominator_sqr = np.absolute(denominator_sqr_signed)
      denominator = _sqrt(denominator_sqr)
  
      # Comparisons using a tolerance can change results if the
      # covariance has a similar order of magnitude
      if denominator == 0.0:
          correlation_xy_sqr = denominator.dtype.type(0)
      else:
          correlation_xy_sqr = covariance_xy_sqr / denominator
  
      return Stats(covariance_xy=covariance_xy_sqr,
                   correlation_xy=correlation_xy_sqr,
                   variance_x=variance_x_sqr,
                   variance_y=variance_y_sqr)
docs: Compute the distance stats using the fast algorithm.