From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Sat, 17 Jan 2015 16:05:10 +0000 (-0600)
Subject: Improve an error message and provide guidance.
X-Git-Tag: v8.3.0-rc1~529^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78b11aa1bd2b01aa4566a07aa5c1c94ecfd59a0a;p=dealii.git

Improve an error message and provide guidance.

In response to a recent question on the mailing list.
---

diff --git a/source/fe/fe_q.cc b/source/fe/fe_q.cc
index 6ffdaf1f59..fe8fd248ed 100644
--- a/source/fe/fe_q.cc
+++ b/source/fe/fe_q.cc
@@ -36,7 +36,9 @@ FE_Q<dim,spacedim>::FE_Q (const unsigned int degree)
 {
   Assert (degree > 0,
           ExcMessage ("This element can only be used for polynomial degrees "
-                      "greater than zero"));
+                      "greater than zero. If you want an element of polynomial "
+                      "degree zero, then it cannot be continuous and you "
+                      "will want to use FE_DGQ<dim>(0)."));
   std::vector<Point<1> > support_points_1d(degree+1);
   for (unsigned int i=0; i<=degree; ++i)
     support_points_1d[i][0] = static_cast<double>(i)/degree;