Merge pull request dealii#18864 from peterrum/mg_transfer_mf_clean_up

MGTransferMF: clean up

Author: marcfehling

doc/news/changes/incompatibilities/20250912Munch

@@ -0,0 +1,4 @@
+Removed: The classes MGTransferMF, MGTransferGlobalCoarsening, MGTransferBlockMF, and MGTransferBlockGlobalCoarsening
+have been deprecated. Their functionalities are now part of MGTransferMatrixFree and MGTransferBlockMatrixFree.
+<br>
+(Peter Munch, 2025/09/12)

examples/step-37/doc/results.dox

@@ -684,7 +684,7 @@ one hand, increasing the polynomial degree to three or four will further
 improve the time per unknown. (Even higher degrees typically get slower again,
 because the multigrid iteration counts increase slightly with the chosen
 simple smoother. One could then use hybrid multigrid algorithms to use
-polynomial coarsening through MGTransferGlobalCoarsening, to reduce the impact
+polynomial coarsening through MGTransferMatrixFree, to reduce the impact
 of the coarser level on the communication latency.) A more significant
 improvement can be obtained by data-locality optimizations. The class
 PreconditionChebyshev, when combined with a `DiagonalMatrix` inner

examples/step-59/doc/results.dox

@@ -357,8 +357,8 @@ Another way of extending the program would be to include support for adaptive
 meshes. While the classical approach of defining interface operations at edges
 of different refinement level, as discussed in step-39, is one possibility,
 for Poisson-type problems another option is typically more beneficial. Using
-the class MGTransferGlobalCoarsening, which is explained in the step-75
-tutorial program, one can deal with meshes of hanging nodes on all levels. An
+the class MGTransferMatrixFree, which is explained in the step-75
+tutorial program, one can also deal with meshes of hanging nodes on all levels. An
 algorithmic improvement can be obtained by combining the discontinuous
 function space with the auxiliary continuous finite element space of the same
 polynomial degree. This idea, introduced by Antonietti et al.
@@ -370,7 +370,7 @@ spaces. The latter work also proposes p-multigrid techniques and combination
 with algebraic multigrid coarse spaces as a means to efficiently solve Poisson
 problems with high-order discontinuous Galerkin discretizations on complicated
 geometries, representing the current state-of-the-art for simple Poisson-type
-problems. The class MGTransferGlobalCoarsening provides features for each of
+problems. The class MGTransferMatrixFree provides features for each of
 these three coarsening variants, the discontinuous-continuous auxiliary
 function concept, p-multigrid, and traditional h-multigrid. The main
 ingredient is to define an appropriate MGTwoLevelTransfer object and call

examples/step-75/doc/intro.dox

@@ -224,7 +224,7 @@ solver to a hybrid multigrid solver.
 We will create a custom hybrid multigrid preconditioner with the special
 level requirements as described above with the help of the existing
 global-coarsening infrastructure via the use of
-MGTransferGlobalCoarsening.
+MGTransferMatrixFree.
 
 
 <h3>The test case</h3>

examples/step-75/step-75.cc

@@ -635,7 +635,7 @@ namespace Step75
   // The above function deals with the actual solution for a given sequence of
   // multigrid objects. This functions creates the actual multigrid levels, in
   // particular the operators, and the transfer operator as a
-  // MGTransferGlobalCoarsening object.
+  // MGTransferMatrixFree object.
   template <typename VectorType, typename OperatorType, int dim>
   void solve_with_gmg(SolverControl                    &solver_control,
                       const OperatorType               &system_matrix,
@@ -804,7 +804,7 @@ namespace Step75
                                   constraints[level + 1],
                                   constraints[level]);
 
-    MGTransferGlobalCoarsening<dim, VectorType> transfer(
+    MGTransferMatrixFree<dim, typename VectorType::value_type> transfer(
       transfers, [&](const auto l, auto &vec) {
         operators[l]->initialize_dof_vector(vec);
       });

examples/step-87/doc/results.dox

@@ -257,7 +257,7 @@ the computational mesh. This is useful if one wants to output the results
 on a coarser mesh or one does not want to output 3D results but instead 2D
 slices. In addition, MGTwoLevelTransferNonNested allows to prolongate solutions
 and restrict residuals between two independent meshes. By passing a sequence
-of such two-level transfer operators to MGTransferMF and, finally, to Multigrid,
+of such two-level transfer operators to MGTransferMatrixFree and, finally, to Multigrid,
 non-nested multigrid can be computed.
 - Utilities::MPI::RemotePointEvaluation can be used to couple non-matching
 grids via surfaces (example: fluid-structure interaction, independently created

include/deal.II/multigrid/mg_transfer_global_coarsening.h

@@ -138,19 +138,20 @@ namespace MGTransferGlobalCoarseningTools
 
 
 template <int dim, typename Number>
-using MGTransferMF = MGTransferMatrixFree<dim, Number>;
+using MGTransferMF DEAL_II_DEPRECATED_EARLY = MGTransferMatrixFree<dim, Number>;
 
 template <int dim, typename Number>
-using MGTransferBlockMF = MGTransferBlockMatrixFree<dim, Number>;
+using MGTransferBlockMF DEAL_II_DEPRECATED_EARLY =
+  MGTransferBlockMatrixFree<dim, Number>;
 
 template <int dim, typename VectorType>
-using MGTransferGlobalCoarsening =
+using MGTransferGlobalCoarsening DEAL_II_DEPRECATED_EARLY =
   MGTransferMatrixFree<dim,
                        typename VectorType::value_type,
                        ::dealii::MemorySpace::Host>;
 
 template <int dim, typename VectorType>
-using MGTransferBlockGlobalCoarsening =
+using MGTransferBlockGlobalCoarsening DEAL_II_DEPRECATED_EARLY =
   MGTransferBlockMatrixFree<dim, typename VectorType::value_type>;