\[ \frac{\partial f}{\partial t} + \upsilon \frac{\partial f}{\partial x} - E(t,x) \frac{\partial f}{\partial \upsilon} = 0 \]
\[ \frac{\partial E}{\partial t} = - J = \int f\upsilon \; d\upsilon \]
3.7 Conclusion ← → 4.1 Algorithm