One more xref.

git-svn-id: https://svn.dealii.org/trunk@21300 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-45/doc/intro.dox b/deal.II/examples/step-45/doc/intro.dox
index af339a73c642fd67ecbb2852f181673a908c3659..92e860f95f9b494fb76b43623e9088163c6ed9eb 100644 (file)
--- a/deal.II/examples/step-45/doc/intro.dox
+++ b/deal.II/examples/step-45/doc/intro.dox
@@ -55,7 +55,8 @@ constraints:
 @f{align*}
   U_{\text{periodic}(i)} = U_i, \qquad \forall i \in {\cal I}_b. 
 @f}
-Now, this is exactly the sort of constraint that the ConstraintMatrix class
+Now, this is exactly the sort of constraint that the ConstraintMatrix class,
+first introduced in step-6,
 handles and can enforce in a linear system. Consequently, the main point of this
 program is how we fill the ConstraintMatrix object that stores these
 constraints, and how this is applied to the resulting linear system.