repair broken eq ref

Doc/UserManual/theoryapp.tex

@@ -298,10 +298,10 @@ The $T$--matrix element for scattering between the asymptotic states $\Psi_{0\al
   & = \braket{\Psi_{0\beta}}{V_1}{\Psi^+_{1\alpha}} + \braket{\Psi^-_{1\beta}}{T_2}{\Psi^+_{1\alpha}} \; ,
 \end{align*}
 with $T_2 = V_2 + V_2G^+_2V_2$. By approximating this last term using $T_2 \simeq V_2$, one arrives at the distorted wave Born approximation:
-\begin{equation*}
+\begin{equation}
   \label{eq:tdwba}
    T^+_{\alpha\beta} \simeq \braket{\Psi_{0\beta}}{V_1}{\Psi^+_{1\alpha}} + \braket{\Psi^-_{1\beta}}{V_2}{\Psi^+_{1\alpha}} \; .
-\end{equation*}
+\end{equation}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \subsection{Multilayer systems}