# Changes

$\left\{ \begin{array}{l} \dfrac{1}{\mu} \dot{x} + Q(V(t), x(t)) = \dfrac{1}{\mu} \dot{x} - I(t) = 0\\ H(x) = \left\{ \begin{array}{l}$
It is then useful to compute the derivativesfor the current and for the constitutive relation $\dfrac{\partial I}{\partial x} = -\dfrac{H'(x)}{H(x)^2}$ $\dfrac{\partial I}{\partial V} = \dfrac{1}{H}$