From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Mon, 14 Jun 2021 22:56:26 +0000 (-0600)
Subject: Add an exception to check that an element exists.
X-Git-Tag: v9.4.0-rc1~1221^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af8d0194d1eb789a9d70be6487006279f8d904b0;p=dealii.git

Add an exception to check that an element exists.
---

diff --git a/source/lac/petsc_vector_base.cc b/source/lac/petsc_vector_base.cc
index de27a60c3b..d4aae2a97a 100644
--- a/source/lac/petsc_vector_base.cc
+++ b/source/lac/petsc_vector_base.cc
@@ -73,6 +73,11 @@ namespace PETScWrappers
           else
             {
               // ghost entry
+              Assert(vector.ghost_indices.is_element(index),
+                     ExcMessage(
+                       "You are trying to access an element of a vector "
+                       "that is neither a locally owned element nor a "
+                       "ghost element of the vector."));
               const size_type ghostidx =
                 vector.ghost_indices.index_within_set(index);