Fix typo in computation of speed of sound

diff --git a/examples/step-67/step-67.cc b/examples/step-67/step-67.cc
index 39653594d53c24f37a60a9a68a4f757466e96f7a..d33d595ea43ae36426e670606d6cc37caf19f519 100644 (file)
--- a/examples/step-67/step-67.cc
+++ b/examples/step-67/step-67.cc
@@ -565,7 +565,7 @@ namespace Euler_DG
   // \frac{\lambda}{2}\left[\mathbf{w}^--\mathbf{w}^+\right]\otimes
   // \mathbf{n^-}$, where the factor $\lambda =
   // \max\left(\|\mathbf{u}^-\|+c^-, \|\mathbf{u}^+\|+c^+\right)$ gives the
-  // maximal wave speed and $c = \sqrt{\lambda p / \rho}$ is the speed of
+  // maximal wave speed and $c = \sqrt{\gamma p / \rho}$ is the speed of
   // sound. Here, we choose two modifications of that expression for reasons
   // of computational efficiency, given the small impact of the flux on the
   // solution. For the above definition of the factor $\lambda$, we would need