In this analysis:
The functions are defined as:
\( \quad \quad \text{JF} = \frac{1 - f}{1 + f} \quad \quad \quad \text{SEF} = 1 - f \)
Expressed in terms of each other:
\( \quad \quad \text{SEF}(\text{JF}) = \frac{2 \times \text{JF}}{1 + \text{JF}} \quad \quad \quad \text{JF}(\text{SEF}) = \frac{\text{SEF}}{2 - \text{SEF}} \)
Differences:
\( \quad \quad \text{SEF} - \text{JF} = \frac{\text{JF}(1 - \text{JF})}{1 + \text{JF}} \quad\) as a function of \( \text{JF} \)
\( \quad \quad \text{SEF} - \text{JF} = \frac{\text{SEF}(1 - \text{SEF})}{2 - \text{SEF}} \quad \) as a function of \( \text{SEF} \)