[WIP]

Author: schnellerhase

cpp/dolfinx/CMakeLists.txt

@@ -17,9 +17,9 @@ set(DOLFINX_DIRS
     io
     la
     mesh
+    multigrid
     nls
     refinement
-    transfer
 )
 
 # Add source to dolfinx target, and get sets of header files

cpp/dolfinx/transfer/CMakeLists.txt renamed to cpp/dolfinx/multigrid/CMakeLists.txt

@@ -1,4 +1,4 @@
-set(HEADERS_transfer
+set(HEADERS_multigrid
     ${CMAKE_CURRENT_SOURCE_DIR}/transfer_matrix.h
     PARENT_SCOPE
 )

cpp/dolfinx/transfer/transfer_matrix.h renamed to cpp/dolfinx/multigrid/transfer_matrix.h

@@ -10,15 +10,18 @@
 #include <concepts>
 #include <cstdint>
 #include <iterator>
+#include <stdexcept>
 #include <vector>
 
+#include <basix/element-families.h>
+
 #include "dolfinx/common/IndexMap.h"
 #include "dolfinx/fem/FunctionSpace.h"
 #include "dolfinx/la/SparsityPattern.h"
 #include "dolfinx/la/utils.h"
 #include "dolfinx/mesh/Mesh.h"
 
-namespace dolfinx::transfer
+namespace dolfinx::multigrid
 {
 
 template <std::floating_point T>
@@ -79,8 +82,7 @@ inclusion_mapping(const dolfinx::mesh::Mesh<T>& mesh_from,
   // other processes.
   std::vector<std::int64_t> result(map.size(), -1);
   MPI_Allreduce(map.data(), result.data(), map.size(),
-                dolfinx::MPI::mpi_type<std::int64_t>(), MPI_MAX,
-                mesh_from.comm());
+                dolfinx::MPI::mpi_t<std::int64_t>, MPI_MAX, mesh_from.comm());
 
   assert(std::ranges::all_of(result, [](auto e) { return e >= 0; }));
   return result;
@@ -92,7 +94,18 @@ create_sparsity_pattern(const dolfinx::fem::FunctionSpace<T>& V_from,
                         const dolfinx::fem::FunctionSpace<T>& V_to,
                         const std::vector<std::int64_t>& inclusion_map)
 {
-  // TODO: P1 and which elements supported?
+  if (*V_from.element() != *V_to.element())
+    throw std::runtime_error(
+        "Transfer between different element types not supported");
+
+  if (V_from.element()->basix_element().family() != basix::element::family::P)
+    throw std::runtime_error("Only Lagrange elements supported");
+
+  if (V_from.element()->basix_element().degree() != 1)
+    throw std::runtime_error("Only piecewise linear elements supported");
+
+  // TODO: mixed elements? value shapes? DG?
+
   auto mesh_from = V_from.mesh();
   auto mesh_to = V_to.mesh();
   assert(mesh_from);
@@ -167,11 +180,21 @@ void assemble_transfer_matrix(la::MatSet<T> auto mat_set,
                               const std::vector<std::int64_t>& inclusion_map,
                               std::function<T(std::int32_t)> weight)
 {
-  // TODO: P1 and which elements supported?
+  if (*V_from.element() != *V_to.element())
+    throw std::runtime_error(
+        "Transfer between different element types not supported");
+
+  if (V_from.element()->basix_element().family() != basix::element::family::P)
+    throw std::runtime_error("Only Lagrange elements supported");
+
+  if (V_from.element()->basix_element().degree() != 1)
+    throw std::runtime_error("Only piecewise linear elements supported");
+
+  // TODO: mixed elements? value shapes? DG?
+
   auto mesh_from = V_from.mesh();
   auto mesh_to = V_to.mesh();
   assert(mesh_from);
-  assert(mesh_to);
 
   MPI_Comm comm = mesh_from->comm();
   {
@@ -227,7 +250,7 @@ void assemble_transfer_matrix(la::MatSet<T> auto mat_set,
         // asserted.
         std::int32_t distance = (n == local_dof_to) ? 0 : 1;
         mat_set(std::vector<int32_t>{dof_from_v[0]}, std::vector<int32_t>{n},
-                std::vector<double>{weight(distance)});
+                std::vector<T>{weight(distance)});
       }
     }
   }

cpp/test/CMakeLists.txt

@@ -48,7 +48,7 @@ add_executable(
   mesh/refinement/interval.cpp
   mesh/refinement/option.cpp
   mesh/refinement/rectangle.cpp
-  transfer/transfer_matrix.cpp
+  multigrid/transfer_matrix.cpp
   ${CMAKE_CURRENT_BINARY_DIR}/poisson.c
 )
 target_link_libraries(unittests PRIVATE Catch2::Catch2WithMain dolfinx)