From 61b03166c9fca213f4c3bd0b135df47a6fc62ee5 Mon Sep 17 00:00:00 2001
From: Yimin Jin <jinym@cea-igp.ac.cn>
Date: Thu, 18 Jan 2024 12:15:57 +0800
Subject: [PATCH] fix bug in function
 DoFCellAccessor::distribute_local_to_global() and add a test

---
 include/deal.II/dofs/dof_accessor.templates.h |  2 +-
 tests/dofs/dof_accessor_04.cc                 | 86 +++++++++++++++++++
 tests/dofs/dof_accessor_04.output             | 20 +++++
 3 files changed, 107 insertions(+), 1 deletion(-)
 create mode 100644 tests/dofs/dof_accessor_04.cc
 create mode 100644 tests/dofs/dof_accessor_04.output

diff --git a/include/deal.II/dofs/dof_accessor.templates.h b/include/deal.II/dofs/dof_accessor.templates.h
index a22f0ec5f5..ff3170f960 100644
--- a/include/deal.II/dofs/dof_accessor.templates.h
+++ b/include/deal.II/dofs/dof_accessor.templates.h
@@ -2957,7 +2957,7 @@ DoFCellAccessor<dimension_, space_dimension_, level_dof_access>::
     {
       global_matrix.add(dof_indices[i],
                         n_dofs,
-                        dof_indices.begin(),
+                        dof_indices.data(),
                         &local_matrix(i, 0));
       global_vector(dof_indices[i]) += local_vector(i);
     }
diff --git a/tests/dofs/dof_accessor_04.cc b/tests/dofs/dof_accessor_04.cc
new file mode 100644
index 0000000000..9f88b53f75
--- /dev/null
+++ b/tests/dofs/dof_accessor_04.cc
@@ -0,0 +1,86 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2021 - 2023 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+// Test DoFCellAccessor::distribute_local_to_global(
+// local_matrix, local_vector, global_matrix, global_vector) 
+
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/dofs/dof_handler.h>
+#include <deal.II/dofs/dof_tools.h>
+#include <deal.II/fe/fe_q.h>
+#include <deal.II/lac/dynamic_sparsity_pattern.h>
+#include <deal.II/lac/sparse_matrix.h>
+#include <deal.II/lac/full_matrix.h>
+#include <deal.II/lac/vector.h>
+
+#include <iostream>
+
+int main()
+{
+  using namespace dealii;
+
+  // create the triangulation
+  Triangulation<2> tria;
+  GridGenerator::hyper_cube(tria, -1, 1);
+  tria.refine_global(1);
+
+  // distribute dofs
+  DoFHandler<2> dof_handler(tria);
+
+  FE_Q<2> fe(1);
+  dof_handler.distribute_dofs(fe);
+
+  // create the global matrix and global vector
+  DynamicSparsityPattern dsp(dof_handler.n_dofs());
+  DoFTools::make_sparsity_pattern(dof_handler, dsp);
+  SparsityPattern sp;
+  sp.copy_from(dsp);
+
+  SparseMatrix<double> global_matrix(sp);
+  Vector<double> global_vector(dof_handler.n_dofs());
+
+  // create local matrix and local vector
+  FullMatrix<double> local_matrix(fe.dofs_per_cell, fe.dofs_per_cell);
+  Vector<double> local_vector(fe.dofs_per_cell);
+  for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
+  {
+    local_vector(i) = i + 1;
+    for (unsigned int j = 0; j < fe.dofs_per_cell; ++j)
+      local_matrix(i, j) = i * fe.dofs_per_cell + j + 1;
+  }
+
+  // call function distribute_local_to_global()
+  auto cell = dof_handler.begin_active();
+  cell->distribute_local_to_global(local_matrix, local_vector, global_matrix, global_vector);
+
+  // output the local matrix and local vector
+  std::cout << "local matrix:" << std::endl;
+  local_matrix.print_formatted(std::cout, 0, false);
+
+  std::cout << "local vector:" << std::endl;
+  local_vector.print(std::cout, 0, false);
+  
+  std::cout << std::endl;
+
+  // output the global matrix and global vector
+  std::cout << "global matrix:" << std::endl;
+  global_matrix.print_formatted(std::cout, 0, false);
+
+  std::cout << "global vector:" << std::endl;
+  global_vector.print(std::cout, 0, false);
+
+  return 0;
+}
diff --git a/tests/dofs/dof_accessor_04.output b/tests/dofs/dof_accessor_04.output
new file mode 100644
index 0000000000..d005b76f35
--- /dev/null
+++ b/tests/dofs/dof_accessor_04.output
@@ -0,0 +1,20 @@
+local matrix:
+ 1  2  3  4 
+ 5  6  7  8 
+ 9 10 11 12 
+13 14 15 16 
+local vector:
+1 2 3 4 
+
+global matrix:
+ 1  2  3  4                
+ 5  6  7  8  0  0          
+ 9 10 11 12        0  0    
+13 14 15 16  0  0  0  0  0 
+    0     0  0  0          
+    0     0  0  0     0  0 
+       0  0        0  0    
+       0  0     0  0  0  0 
+          0     0     0  0 
+global vector:
+1 2 3 4 0 0 0 0 0
-- 
2.39.5