From: Zhuoran Wang <zhrwang@rams.colostate.edu>
Date: Tue, 24 Mar 2020 05:46:22 +0000 (-0600)
Subject: Introduce face notations to introduction.
X-Git-Tag: v9.2.0-rc1~35^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f9aa2d6589bfbd5a2e82ee0ae58ca317f41ce551;p=dealii.git

Introduce face notations to introduction.
---

diff --git a/examples/step-47/doc/intro.dox b/examples/step-47/doc/intro.dox
index 86fab3feed..d401745958 100644
--- a/examples/step-47/doc/intro.dox
+++ b/examples/step-47/doc/intro.dox
@@ -230,7 +230,10 @@ As mentioned, this method relies on the use of $C^0$ Lagrange finite
 elements where the $C^1$ continuity requirement is relaxed and has
 been replaced with interior penalty techniques. To derive this method,
 we consider a $C^0$ shape function $v_h$ which vanishes on
-$\partial\Omega$. Since the higher order derivatives of $v_h$ have two
+$\partial\Omega$. We introduce notation $ \mathbb{F} $ as the set of
+all faces of $\mathbb{T}$, $ \mathbb{F}^b $ as the set of boundary faces,
+and $ \mathbb{F}^i $ as the set of interior faces for use further down below.
+Since the higher order derivatives of $v_h$ have two
 values on each interface $e\in \mathbb{F}$ (shared by the two cells
 $K_{+},K_{-} \in \mathbb{T}$), we cope with this discontinuity by
 defining the following single-valued functions on $e$: