Missing ' in the comoving Gadget-SPH lagrangian.

theory/Cosmology/coordinates.tex

@@ -35,7 +35,7 @@ respectively. Following \cite{Peebles1980} (ch.7), we introduce the
 gauge transformation $\Lag \rightarrow \Lag + \frac{d}{dt}\Psi$ with
 $\Psi \equiv \frac{1}{2}a\dot{a}\mathbf{r}_i^2$ and obtain
 \begin{align}
-  \Lag &= \frac{1}{2}m_ia^2 \dot{\mathbf{r}}_i^2 -
+  \Lag &= \frac{1}{2}m_ia^2 \dot{\mathbf{r}}_i'^2 -
   \frac{1}{\gamma-1}m_iA_i'\left(\frac{\rho_i'}{a^3}\right)^{\gamma-1}
   -\frac{\phi'}{a},\\
   \phi' &= a\phi + \frac{1}{2}a^2\ddot{a}\mathbf{r}_i'^2,\nonumber