From: David Wells <wellsd2@rpi.edu>
Date: Sat, 9 Jan 2016 20:37:39 +0000 (-0500)
Subject: Fix a bug with the call to SolutionTransfer.
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F14%2Fhead;p=code-gallery.git

Fix a bug with the call to SolutionTransfer.
---

diff --git a/cdr/solver/cdr.cc b/cdr/solver/cdr.cc
index 0be13d4..da832e6 100644
--- a/cdr/solver/cdr.cc
+++ b/cdr/solver/cdr.cc
@@ -273,11 +273,23 @@ void CDRProblem<dim>::refine_mesh()
 
   setup_dofs();
 
+  // The <code>solution_transfer</code> object stores a pointer to
+  // <code>locally_relevant_solution</code>, so when
+  // parallel::distributed::SolutionTransfer::interpolate is called it uses
+  // those values to populate <code>temporary</code>.
   TrilinosWrappers::MPI::Vector temporary
-  (locally_owned_dofs, mpi_communicator);
+    (locally_owned_dofs, mpi_communicator);
   solution_transfer.interpolate(temporary);
-  locally_relevant_solution = temporary;
-  constraints.distribute(locally_relevant_solution);
+  // After <code>temporary</code> has the correct value, this call correctly
+  // populates <code>completely_distributed_solution</code>, which had its
+  // index set updated above with the call to <code>setup_dofs</code>.
+  completely_distributed_solution = temporary;
+  // Constraints cannot be applied to
+  // @ref GlossGhostedVector "vectors with ghost entries" since the ghost
+  // entries are write only, so this first goes through the completely
+  // distributed vector.
+  constraints.distribute(completely_distributed_solution);
+  locally_relevant_solution = completely_distributed_solution;
   setup_system();
 }