Link to step-21

git-svn-id: https://svn.dealii.org/trunk@14128 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-23/doc/intro.dox b/deal.II/examples/step-23/doc/intro.dox
index de59cf8f978eb81dc8a8e633648db12dbd43ccb5..b11f5ae957bbe201f7d2f322a1d660b3c9a4c524 100644 (file)
--- a/deal.II/examples/step-23/doc/intro.dox
+++ b/deal.II/examples/step-23/doc/intro.dox
@@ -2,7 +2,8 @@
 <h1>Introduction</h1>
 
 This is the first of a number of tutorial programs that will finally
-cover time-dependent problems. In particular, this program introduces
+cover "real" time-dependent problems, not the slightly odd form of time
+dependence found in @ref step_18 "step-18" or the DAE model of @ref step_21 "step-21". In particular, this program introduces
 the wave equation in a bounded domain. Later, @ref step_24 "step-24"
 will consider an example of absorbing boundary conditions, and @ref
 step_25 "step-25" a kind of nonlinear wave equation producing