[NL] LeastSqExt: Fix global vector creation.

Especially the creation of ghost nodes.

NumLib/Extrapolation/LocalLinearLeastSquaresExtrapolator.cpp

@@ -47,12 +47,39 @@ void LocalLinearLeastSquaresExtrapolator::extrapolate(
 {
     auto const num_nodal_dof_result =
         _dof_table_single_component.dofSizeWithoutGhosts() * num_components;
+
+    std::vector<GlobalIndexType> ghost_indices;
+    {  // Create num_components times version of ghost_indices arranged by
+       // location. For example for 3 components and ghost_indices {5,6,10} we
+       // compute {15, 16, 17,  18, 19, 20,  30, 31, 32}.
+        auto const& single_component_ghost_indices =
+            _dof_table_single_component.getGhostIndices();
+        auto const single_component_ghost_indices_size =
+            single_component_ghost_indices.size();
+        ghost_indices.reserve(single_component_ghost_indices_size *
+                              num_components);
+        for (unsigned i = 0; i < single_component_ghost_indices_size; ++i)
+        {
+            for (unsigned c = 0; c < num_components; ++c)
+            {
+                ghost_indices.push_back(
+                    single_component_ghost_indices[i] * num_components + c);
+            }
+        }
+    }
+
     if (!_nodal_values ||
-        static_cast<std::size_t>(_nodal_values->size()) != num_nodal_dof_result)
+#ifdef USE_PETSC
+        static_cast<std::size_t>(_nodal_values->getLocalSize() +
+                                 _nodal_values->getGhostSize())
+#else
+        _nodal_values->size()
+#endif
+            != num_nodal_dof_result)
     {
         _nodal_values = MathLib::MatrixVectorTraits<GlobalVector>::newInstance(
-            MathLib::MatrixSpecifications{
-                num_nodal_dof_result, num_nodal_dof_result, nullptr, nullptr});
+            {num_nodal_dof_result, num_nodal_dof_result, &ghost_indices,
+             nullptr});
     }
     _nodal_values->setZero();