From: tcclevenger <tcleven@clemson.edu>
Date: Wed, 15 Apr 2020 18:04:18 +0000 (-0400)
Subject: extract_constant_modes fix
X-Git-Tag: v9.2.0-rc1~224^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F9896%2Fhead;p=dealii.git

extract_constant_modes fix
---

diff --git a/source/dofs/dof_tools.cc b/source/dofs/dof_tools.cc
index 55f4c3553c..05b451da93 100644
--- a/source/dofs/dof_tools.cc
+++ b/source/dofs/dof_tools.cc
@@ -1265,6 +1265,14 @@ namespace DoFTools
                          const ComponentMask &           component_mask,
                          std::vector<std::vector<bool>> &constant_modes)
   {
+    // If there are no locally owned DoFs, return with an empty
+    // constant_modes object:
+    if (dof_handler.n_locally_owned_dofs() == 0)
+      {
+        constant_modes = std::vector<std::vector<bool>>(0);
+        return;
+      }
+
     const unsigned int n_components = dof_handler.get_fe(0).n_components();
     Assert(component_mask.represents_n_components(n_components),
            ExcDimensionMismatch(n_components, component_mask.size()));