diff --git a/docs/theory.md b/docs/theory.md
index fe7c73f..4e95493 100644
--- a/docs/theory.md
+++ b/docs/theory.md
@@ -147,7 +147,10 @@ $$
 
 is rearranged to give:
 
-$$ u_r^{n+1} \approx \left[ \frac{1-\left(1-\alpha\right)\hat\beta c\Delta t\hat\sigma}{1+\alpha\hat\beta c\Delta t\hat\sigma} \right] u^n_r + \left[ \frac{\hat\beta\hat\sigma\Delta t}{1+\alpha\hat\beta c\Delta t\hat\sigma} \right] \phi^\lambda $$
+$$ u_r^{n+1} \approx
+\left[ \frac{1-\left(1-\alpha\right)\hat\beta c\Delta t\hat\sigma}{1+\alpha\hat\beta c\Delta t\hat\sigma} \right] u^n_r +
+\left[ \frac{\hat\beta\hat\sigma\Delta t}{1+\alpha\hat\beta c\Delta t\hat\sigma} \right] \phi^\lambda
+$$
 
 which allows us to write: