--- manual/s_phys_pkgs/text/obcs.tex	2011/03/16 16:57:01	1.12
+++ manual/s_phys_pkgs/text/obcs.tex	2011/05/02 09:11:20	1.13
@@ -384,7 +384,7 @@
   a phase velocity estimated as
   $\frac{1}{2}\frac{\partial\chi}{\partial{t}}/\frac{\partial\chi}{\partial{x}}$. The
   numerical scheme is (as an example for an eastern boundary):
-  \[\chi_{i,j,k}^{n+1} =   \chi_{i,j,k}^{n} + \Delta{t} 
+  \[\chi_{i_{b},j,k}^{n+1} =   \chi_{i_{b},j,k}^{n} + \Delta{t} 
   (u^{n+1}+c)_{i_{b},j,k}\frac{\chi_{i_{b},j,k}^{n}
     - \chi_{i_{b}-1,j,k}^{n}}{\Delta{x}_{i_{b},j}^{C}}\mbox{, if }u_{i_{b},j,k}^{n+1}>0,
   \] where $i_{b}$ is the boundary index.