 [{ \rho ^\varepsilon _0}(-A), { \rho ^\varepsilon _0}(-A)]$ and we can write for any $t \in [0, t ^{ \varepsilon}_0]$ $$\frac{{ \varepsilon}\frac{{ \mathrm{d}}|{ V ^\varepsilon }|}{{ \mathrm{d}}t }}{