From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Sat, 18 May 2019 10:45:56 +0000 (-0600)
Subject: Mention step-61 in the introduction of step-51.
X-Git-Tag: v9.2.0-rc1~1465^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F8238%2Fhead;p=dealii.git

Mention step-61 in the introduction of step-51.
---

diff --git a/examples/step-51/doc/builds-on b/examples/step-51/doc/builds-on
index f1818ebf1b..da87e7fb0a 100644
--- a/examples/step-51/doc/builds-on
+++ b/examples/step-51/doc/builds-on
@@ -1 +1 @@
-step-7 step-9
+step-7 step-9 step-61
diff --git a/examples/step-51/doc/intro.dox b/examples/step-51/doc/intro.dox
index 1ab7b75c79..fb63724b66 100644
--- a/examples/step-51/doc/intro.dox
+++ b/examples/step-51/doc/intro.dox
@@ -41,7 +41,7 @@ this goal by formulating the mathematical problem using Dirichlet-to-Neumann
 mappings.  The partial differential equations are first written as a first
 order system, and each field is then discretized via a DG method.  At this
 point, the  single-valued "trace" values on the skeleton of the
-mesh, i.e. element faces, are taken to be independent unknown quantities.
+mesh, i.e., element faces, are taken to be independent unknown quantities.
 This yields unknowns in the discrete formulation that fall into two categories:
 - Face unknowns that only couple with the cell unknowns from both sides of the face;
 - Cell unknowns that only couple with the cell and face unknowns
@@ -101,6 +101,13 @@ super-convergence property can be used to post-process a new approximate
 solution that converges at the rate $\mathcal{O}(h^{p+2})$.
 
 
+<h4> Alternative approaches </h4>
+
+The hybridizable discontinuous Galerkin method is only one way in
+which the problems of the discontinuous Galerkin method can be
+addressed. Another idea is what is called the "weak Galerkin"
+method. It is explored in step-61.
+
 
 <h3> HDG applied to the convection-diffusion problem </h3>