Better notation for \mu_ij term in the cosmology notes.

theory/Cosmology/coordinates.tex

@@ -109,8 +109,8 @@ viscosity ``tensor'' $\Pi_{ij} \equiv \frac{1}{2}\alpha_{\rm visc} v_{\rm
   \omega_{ij}' &= \left(\mathbf{v}_i' - \mathbf{v}_j'\right) \cdot
   \left(\mathbf{r}_i' - \mathbf{r}_j'\right), \\
   \mu_{ij}' &=
-  a^{(3\gamma-5)/2} \left(\omega_{ij}' + a^2H\left(\mathbf{r}_i' -
-  \mathbf{r}_j'\right)^2 \right) / |\mathbf{r}_i' - \mathbf{r}_j' |,
+  a^{(3\gamma-5)/2} \left(\omega_{ij}' + a^2H\left|\mathbf{r}_i' -
+  \mathbf{r}_j'\right|^2 \right) / |\mathbf{r}_i' - \mathbf{r}_j' |,
   \\
   v_{\rm sig}' &= c_i' + c_j' - 3 \mu_{ij}'.
 \end{align}