Reference documentation for deal.II version 9.4.0
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mg_transfer_block.cc
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2//
3// Copyright (C) 2003 - 2021 by the deal.II authors
4//
5// This file is part of the deal.II library.
6//
7// The deal.II library is free software; you can use it, redistribute
8// it, and/or modify it under the terms of the GNU Lesser General
9// Public License as published by the Free Software Foundation; either
10// version 2.1 of the License, or (at your option) any later version.
11// The full text of the license can be found in the file LICENSE.md at
12// the top level directory of deal.II.
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15
16
18
21
22#include <deal.II/fe/fe.h>
23
24#include <deal.II/grid/tria.h>
26
30#include <deal.II/lac/vector.h>
31
34#include <deal.II/multigrid/mg_transfer_block.templates.h>
35
36#include <algorithm>
37#include <iostream>
38#include <numeric>
39#include <utility>
40
42
43namespace
44{
52 template <int dim, typename number, int spacedim>
53 void
54 reinit_vector_by_blocks(
55 const ::DoFHandler<dim, spacedim> & dof_handler,
57 const std::vector<bool> & sel,
58 std::vector<std::vector<types::global_dof_index>> &ndofs)
59 {
60 std::vector<bool> selected = sel;
61 // Compute the number of blocks needed
62 const unsigned int n_selected =
63 std::accumulate(selected.begin(), selected.end(), 0u);
64
65 if (ndofs.size() == 0)
66 {
67 std::vector<std::vector<types::global_dof_index>> new_dofs(
68 dof_handler.get_triangulation().n_levels(),
69 std::vector<types::global_dof_index>(selected.size()));
70 std::swap(ndofs, new_dofs);
71 MGTools::count_dofs_per_block(dof_handler, ndofs);
72 }
73
74 for (unsigned int level = v.min_level(); level <= v.max_level(); ++level)
75 {
76 v[level].reinit(n_selected, 0);
77 unsigned int k = 0;
78 for (unsigned int i = 0;
79 i < selected.size() && (k < v[level].n_blocks());
80 ++i)
81 {
82 if (selected[i])
83 {
84 v[level].block(k++).reinit(ndofs[level][i]);
85 }
86 v[level].collect_sizes();
87 }
88 }
89 }
90
91
98 template <int dim, typename number, int spacedim>
99 void
100 reinit_vector_by_blocks(
101 const ::DoFHandler<dim, spacedim> & dof_handler,
103 const unsigned int selected_block,
104 std::vector<std::vector<types::global_dof_index>> &ndofs)
105 {
106 const unsigned int n_blocks = dof_handler.get_fe().n_blocks();
107 AssertIndexRange(selected_block, n_blocks);
108
109 std::vector<bool> selected(n_blocks, false);
110 selected[selected_block] = true;
111
112 if (ndofs.size() == 0)
113 {
114 std::vector<std::vector<types::global_dof_index>> new_dofs(
115 dof_handler.get_triangulation().n_levels(),
116 std::vector<types::global_dof_index>(selected.size()));
117 std::swap(ndofs, new_dofs);
118 MGTools::count_dofs_per_block(dof_handler, ndofs);
119 }
120
121 for (unsigned int level = v.min_level(); level <= v.max_level(); ++level)
122 {
123 v[level].reinit(ndofs[level][selected_block]);
124 }
125 }
126} // namespace
127
128
129template <typename number>
130template <int dim, typename number2, int spacedim>
131void
133 const DoFHandler<dim, spacedim> &dof_handler,
135 const BlockVector<number2> & src) const
136{
137 reinit_vector_by_blocks(dof_handler, dst, selected_block, sizes);
138 // For MGTransferBlockSelect, the
139 // multilevel block is always the
140 // first, since only one block is
141 // selected.
142 for (unsigned int level = dof_handler.get_triangulation().n_levels();
143 level != 0;)
144 {
145 --level;
146 for (IT i = copy_indices[selected_block][level].begin();
147 i != copy_indices[selected_block][level].end();
148 ++i)
149 dst[level](i->second) = src.block(selected_block)(i->first);
150 }
151}
152
153
154
155template <typename number>
156template <int dim, typename number2, int spacedim>
157void
159 const DoFHandler<dim, spacedim> &dof_handler,
161 const Vector<number2> & src) const
162{
163 reinit_vector_by_blocks(dof_handler, dst, selected_block, sizes);
164 // For MGTransferBlockSelect, the
165 // multilevel block is always the
166 // first, since only one block is selected.
167 for (unsigned int level = dof_handler.get_triangulation().n_levels();
168 level != 0;)
169 {
170 --level;
171 for (IT i = copy_indices[selected_block][level].begin();
172 i != copy_indices[selected_block][level].end();
173 ++i)
174 dst[level](i->second) = src(i->first);
175 }
176}
177
178
179
180template <typename number>
181template <int dim, typename number2, int spacedim>
182void
184 const DoFHandler<dim, spacedim> & dof_handler,
186 const BlockVector<number2> & src) const
187{
188 reinit_vector_by_blocks(dof_handler, dst, selected, sizes);
189 for (unsigned int level = dof_handler.get_triangulation().n_levels();
190 level != 0;)
191 {
192 --level;
193 for (unsigned int block = 0; block < selected.size(); ++block)
194 if (selected[block])
195 for (IT i = copy_indices[block][level].begin();
196 i != copy_indices[block][level].end();
197 ++i)
198 dst[level].block(mg_block[block])(i->second) =
199 src.block(block)(i->first);
200 }
201}
202
203
204
205template <int dim, int spacedim>
206void
208{
209 const FiniteElement<dim> &fe = dof_handler.get_fe();
210 const unsigned int n_blocks = fe.n_blocks();
211 const unsigned int dofs_per_cell = fe.n_dofs_per_cell();
212 const unsigned int n_levels = dof_handler.get_triangulation().n_levels();
213
214 Assert(selected.size() == n_blocks,
216
217 // Compute the mapping between real
218 // blocks and blocks used for
219 // multigrid computations.
220 mg_block.resize(n_blocks);
221 n_mg_blocks = 0;
222 for (unsigned int i = 0; i < n_blocks; ++i)
223 if (selected[i])
224 mg_block[i] = n_mg_blocks++;
225 else
227
228 // Compute the lengths of all blocks
229 sizes.clear();
230 sizes.resize(n_levels, std::vector<types::global_dof_index>(fe.n_blocks()));
232
233 // Fill some index vectors
234 // for later use.
236 // Compute start indices from sizes
237 for (auto &level_blocks : mg_block_start)
238 {
240 for (types::global_dof_index &level_block_start : level_blocks)
241 {
242 const types::global_dof_index t = level_block_start;
243 level_block_start = k;
244 k += t;
245 }
246 }
247
249 static_cast<const DoFHandler<dim, spacedim> &>(dof_handler));
250
252 for (types::global_dof_index &first_index : block_start)
253 {
254 const types::global_dof_index t = first_index;
255 first_index = k;
256 k += t;
257 }
258 // Build index vectors for
259 // copy_to_mg and
260 // copy_from_mg. These vectors must
261 // be prebuilt, since the
262 // get_dof_indices functions are
263 // too slow
264 copy_indices.resize(n_blocks);
265 for (unsigned int block = 0; block < n_blocks; ++block)
266 if (selected[block])
267 copy_indices[block].resize(n_levels);
268
269 // Building the prolongation matrices starts here!
270
271 // reset the size of the array of
272 // matrices. call resize(0) first,
273 // in order to delete all elements
274 // and clear their memory. then
275 // repopulate these arrays
276 //
277 // note that on resize(0), the
278 // shared_ptr class takes care of
279 // deleting the object it points to
280 // by itself
281 prolongation_matrices.resize(0);
282 prolongation_sparsities.resize(0);
283 prolongation_matrices.reserve(n_levels - 1);
284 prolongation_sparsities.reserve(n_levels - 1);
285
286 for (unsigned int i = 0; i < n_levels - 1; ++i)
287 {
290 }
291
292 // two fields which will store the
293 // indices of the multigrid dofs
294 // for a cell and one of its children
295 std::vector<types::global_dof_index> dof_indices_parent(dofs_per_cell);
296 std::vector<types::global_dof_index> dof_indices_child(dofs_per_cell);
297
298 // for each level: first build the
299 // sparsity pattern of the matrices
300 // and then build the matrices
301 // themselves. note that we only
302 // need to take care of cells on
303 // the coarser level which have
304 // children
305
306 for (unsigned int level = 0; level < n_levels - 1; ++level)
307 {
308 // reset the dimension of the
309 // structure. note that for
310 // the number of entries per
311 // row, the number of parent
312 // dofs coupling to a child dof
313 // is necessary. this, is the
314 // number of degrees of freedom
315 // per cell
317 for (unsigned int i = 0; i < n_blocks; ++i)
318 for (unsigned int j = 0; j < n_blocks; ++j)
319 if (i == j)
320 prolongation_sparsities[level]->block(i, j).reinit(
321 sizes[level + 1][i], sizes[level][j], dofs_per_cell + 1);
322 else
323 prolongation_sparsities[level]->block(i, j).reinit(
324 sizes[level + 1][i], sizes[level][j], 0);
325
326 prolongation_sparsities[level]->collect_sizes();
327
329 dof_handler.begin(level);
330 cell != dof_handler.end(level);
331 ++cell)
332 if (cell->has_children())
333 {
334 cell->get_mg_dof_indices(dof_indices_parent);
335
336 Assert(cell->n_children() ==
339 for (unsigned int child = 0; child < cell->n_children(); ++child)
340 {
341 // set an alias to the
342 // prolongation matrix for
343 // this child
344 const FullMatrix<double> &prolongation =
345 dof_handler.get_fe().get_prolongation_matrix(
346 child, cell->refinement_case());
347
348 cell->child(child)->get_mg_dof_indices(dof_indices_child);
349
350 // now tag the entries in the
351 // matrix which will be used
352 // for this pair of parent/child
353 for (unsigned int i = 0; i < dofs_per_cell; ++i)
354 for (unsigned int j = 0; j < dofs_per_cell; ++j)
355 if (prolongation(i, j) != 0)
356 {
357 const unsigned int icomp =
358 fe.system_to_block_index(i).first;
359 const unsigned int jcomp =
360 fe.system_to_block_index(j).first;
361 if ((icomp == jcomp) && selected[icomp])
363 dof_indices_child[i], dof_indices_parent[j]);
364 }
365 }
366 }
367 prolongation_sparsities[level]->compress();
368
370 // now actually build the matrices
372 dof_handler.begin(level);
373 cell != dof_handler.end(level);
374 ++cell)
375 if (cell->has_children())
376 {
377 cell->get_mg_dof_indices(dof_indices_parent);
378
379 Assert(cell->n_children() ==
382 for (unsigned int child = 0; child < cell->n_children(); ++child)
383 {
384 // set an alias to the
385 // prolongation matrix for
386 // this child
387 const FullMatrix<double> &prolongation =
388 dof_handler.get_fe().get_prolongation_matrix(
389 child, cell->refinement_case());
390
391 cell->child(child)->get_mg_dof_indices(dof_indices_child);
392
393 // now set the entries in the
394 // matrix
395 for (unsigned int i = 0; i < dofs_per_cell; ++i)
396 for (unsigned int j = 0; j < dofs_per_cell; ++j)
397 if (prolongation(i, j) != 0)
398 {
399 const unsigned int icomp =
400 fe.system_to_block_index(i).first;
401 const unsigned int jcomp =
402 fe.system_to_block_index(j).first;
403 if ((icomp == jcomp) && selected[icomp])
405 dof_indices_child[i],
406 dof_indices_parent[j],
407 prolongation(i, j));
408 }
409 }
410 }
411 }
412 // impose boundary conditions
413 // but only in the column of
414 // the prolongation matrix
415 if (mg_constrained_dofs != nullptr &&
417 {
418 std::vector<types::global_dof_index> constrain_indices;
419 std::vector<std::vector<bool>> constraints_per_block(n_blocks);
420 for (int level = n_levels - 2; level >= 0; --level)
421 {
423 0)
424 continue;
425
426 // need to delete all the columns in the
427 // matrix that are on the boundary. to achieve
428 // this, create an array as long as there are
429 // matrix columns, and find which columns we
430 // need to filter away.
431 constrain_indices.resize(0);
432 constrain_indices.resize(prolongation_matrices[level]->n(), 0);
436 for (; dof != endd; ++dof)
437 constrain_indices[*dof] = 1;
438
439 unsigned int index = 0;
440 for (unsigned int block = 0; block < n_blocks; ++block)
441 {
442 const types::global_dof_index n_dofs =
443 prolongation_matrices[level]->block(block, block).m();
444 constraints_per_block[block].resize(0);
445 constraints_per_block[block].resize(n_dofs, false);
446 for (types::global_dof_index i = 0; i < n_dofs; ++i, ++index)
447 constraints_per_block[block][i] =
448 (constrain_indices[index] == 1);
449
450 for (types::global_dof_index i = 0; i < n_dofs; ++i)
451 {
453 start_row = prolongation_matrices[level]
454 ->block(block, block)
455 .begin(i),
456 end_row =
457 prolongation_matrices[level]->block(block, block).end(i);
458 for (; start_row != end_row; ++start_row)
459 {
460 if (constraints_per_block[block][start_row->column()])
461 start_row->value() = 0.;
462 }
463 }
464 }
465 }
466 }
467}
468
469template <typename number>
470template <int dim, int spacedim>
471void
473 const DoFHandler<dim, spacedim> &dof_handler,
474 unsigned int select)
475{
476 const FiniteElement<dim> &fe = dof_handler.get_fe();
477 unsigned int n_blocks = dof_handler.get_fe().n_blocks();
478
479 selected_block = select;
480 selected.resize(n_blocks, false);
481 selected[select] = true;
482
483 MGTransferBlockBase::build(dof_handler);
484
485 std::vector<types::global_dof_index> temp_copy_indices;
486 std::vector<types::global_dof_index> global_dof_indices(fe.n_dofs_per_cell());
487 std::vector<types::global_dof_index> level_dof_indices(fe.n_dofs_per_cell());
488
489 for (int level = dof_handler.get_triangulation().n_levels() - 1; level >= 0;
490 --level)
491 {
493 dof_handler.begin_active(level);
494 const typename DoFHandler<dim, spacedim>::active_cell_iterator level_end =
495 dof_handler.end_active(level);
496
497 temp_copy_indices.resize(0);
498 temp_copy_indices.resize(sizes[level][selected_block],
500
501 // Compute coarse level right hand side
502 // by restricting from fine level.
503 for (; level_cell != level_end; ++level_cell)
504 {
505 // get the dof numbers of
506 // this cell for the global
507 // and the level-wise
508 // numbering
509 level_cell->get_dof_indices(global_dof_indices);
510 level_cell->get_mg_dof_indices(level_dof_indices);
511
512 for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
513 {
514 const unsigned int block = fe.system_to_block_index(i).first;
515 if (selected[block])
516 {
517 if (mg_constrained_dofs != nullptr)
518 {
519 if (!mg_constrained_dofs->at_refinement_edge(
520 level, level_dof_indices[i]))
521 temp_copy_indices[level_dof_indices[i] -
522 mg_block_start[level][block]] =
523 global_dof_indices[i] - block_start[block];
524 }
525 else
526 temp_copy_indices[level_dof_indices[i] -
527 mg_block_start[level][block]] =
528 global_dof_indices[i] - block_start[block];
529 }
530 }
531 }
532
533 // now all the active dofs got a valid entry,
534 // the other ones have an invalid entry. Count
535 // the invalid entries and then resize the
536 // copy_indices object. Then, insert the pairs
537 // of global index and level index into
538 // copy_indices.
539 const types::global_dof_index n_active_dofs =
540 std::count_if(temp_copy_indices.begin(),
541 temp_copy_indices.end(),
542 [](const types::global_dof_index index) {
543 return index != numbers::invalid_dof_index;
544 });
545 copy_indices[selected_block][level].resize(n_active_dofs);
546 types::global_dof_index counter = 0;
547 for (types::global_dof_index i = 0; i < temp_copy_indices.size(); ++i)
548 if (temp_copy_indices[i] != numbers::invalid_dof_index)
549 copy_indices[selected_block][level][counter++] =
550 std::pair<types::global_dof_index, unsigned int>(
551 temp_copy_indices[i], i);
552 Assert(counter == n_active_dofs, ExcInternalError());
553 }
554}
555
556
557template <typename number>
558template <int dim, int spacedim>
559void
561 const std::vector<bool> & sel)
562{
563 const FiniteElement<dim> &fe = dof_handler.get_fe();
564 unsigned int n_blocks = dof_handler.get_fe().n_blocks();
565
566 if (sel.size() != 0)
567 {
568 Assert(sel.size() == n_blocks,
569 ExcDimensionMismatch(sel.size(), n_blocks));
570 selected = sel;
571 }
572 if (selected.size() == 0)
573 selected = std::vector<bool>(n_blocks, true);
574
575 MGTransferBlockBase::build(dof_handler);
576
577 std::vector<std::vector<types::global_dof_index>> temp_copy_indices(n_blocks);
578 std::vector<types::global_dof_index> global_dof_indices(fe.n_dofs_per_cell());
579 std::vector<types::global_dof_index> level_dof_indices(fe.n_dofs_per_cell());
580 for (int level = dof_handler.get_triangulation().n_levels() - 1; level >= 0;
581 --level)
582 {
584 dof_handler.begin_active(level);
585 const typename DoFHandler<dim, spacedim>::active_cell_iterator level_end =
586 dof_handler.end_active(level);
587
588 for (unsigned int block = 0; block < n_blocks; ++block)
589 if (selected[block])
590 {
591 temp_copy_indices[block].resize(0);
592 temp_copy_indices[block].resize(sizes[level][block],
594 }
595
596 // Compute coarse level right hand side
597 // by restricting from fine level.
598 for (; level_cell != level_end; ++level_cell)
599 {
600 // get the dof numbers of
601 // this cell for the global
602 // and the level-wise
603 // numbering
604 level_cell->get_dof_indices(global_dof_indices);
605 level_cell->get_mg_dof_indices(level_dof_indices);
606
607 for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
608 {
609 const unsigned int block = fe.system_to_block_index(i).first;
610 if (selected[block])
611 temp_copy_indices[block][level_dof_indices[i] -
612 mg_block_start[level][block]] =
613 global_dof_indices[i] - block_start[block];
614 }
615 }
616
617 for (unsigned int block = 0; block < n_blocks; ++block)
618 if (selected[block])
619 {
620 const types::global_dof_index n_active_dofs =
621 std::count_if(temp_copy_indices[block].begin(),
622 temp_copy_indices[block].end(),
623 [](const types::global_dof_index index) {
624 return index != numbers::invalid_dof_index;
625 });
626 copy_indices[block][level].resize(n_active_dofs);
627 types::global_dof_index counter = 0;
628 for (types::global_dof_index i = 0;
629 i < temp_copy_indices[block].size();
630 ++i)
631 if (temp_copy_indices[block][i] != numbers::invalid_dof_index)
632 copy_indices[block][level][counter++] =
633 std::pair<types::global_dof_index, unsigned int>(
634 temp_copy_indices[block][i], i);
635 Assert(counter == n_active_dofs, ExcInternalError());
636 }
637 }
638}
639
640
641
642// explicit instantiations
643#include "mg_transfer_block.inst"
644
645
cell_iterator end() const
const FiniteElement< dim, spacedim > & get_fe(const unsigned int index=0) const
const Triangulation< dim, spacedim > & get_triangulation() const
active_cell_iterator begin_active(const unsigned int level=0) const
active_cell_iterator end_active(const unsigned int level) const
cell_iterator begin(const unsigned int level=0) const
unsigned int n_dofs_per_cell() const
unsigned int n_blocks() const
std::pair< unsigned int, types::global_dof_index > system_to_block_index(const unsigned int component) const
virtual const FullMatrix< double > & get_prolongation_matrix(const unsigned int child, const RefinementCase< dim > &refinement_case=RefinementCase< dim >::isotropic_refinement) const
size_type n_elements() const
Definition: index_set.h:1834
ElementIterator begin() const
Definition: index_set.h:1520
ElementIterator end() const
Definition: index_set.h:1582
bool have_boundary_indices() const
const IndexSet & get_boundary_indices(const unsigned int level) const
std::vector< unsigned int > mg_block
std::vector< std::vector< types::global_dof_index > > sizes
void build(const DoFHandler< dim, spacedim > &dof_handler)
std::vector< bool > selected
std::vector< types::global_dof_index > block_start
std::vector< std::shared_ptr< BlockSparseMatrix< double > > > prolongation_matrices
std::vector< std::shared_ptr< BlockSparsityPattern > > prolongation_sparsities
SmartPointer< const MGConstrainedDoFs, MGTransferBlockBase > mg_constrained_dofs
std::vector< std::vector< types::global_dof_index > > mg_block_start
std::vector< std::vector< std::vector< std::pair< unsigned int, unsigned int > > > > copy_indices
void copy_to_mg(const DoFHandler< dim, spacedim > &dof_handler, MGLevelObject< Vector< number > > &dst, const Vector< number2 > &src) const
void build(const DoFHandler< dim, spacedim > &dof_handler, unsigned int selected)
void build(const DoFHandler< dim, spacedim > &dof_handler, const std::vector< bool > &selected)
void copy_to_mg(const DoFHandler< dim, spacedim > &dof_handler, MGLevelObject< BlockVector< number > > &dst, const BlockVector< number2 > &src) const
unsigned int n_levels() const
#define DEAL_II_NAMESPACE_OPEN
Definition: config.h:442
#define DEAL_II_NAMESPACE_CLOSE
Definition: config.h:443
unsigned int level
Definition: grid_out.cc:4606
static ::ExceptionBase & ExcNotImplemented()
#define Assert(cond, exc)
Definition: exceptions.h:1473
#define AssertIndexRange(index, range)
Definition: exceptions.h:1732
static ::ExceptionBase & ExcInternalError()
BlockType & block(const unsigned int i)
static ::ExceptionBase & ExcDimensionMismatch(std::size_t arg1, std::size_t arg2)
std::vector< types::global_dof_index > count_dofs_per_fe_block(const DoFHandler< dim, spacedim > &dof, const std::vector< unsigned int > &target_block=std::vector< unsigned int >())
Definition: dof_tools.cc:1980
void count_dofs_per_block(const DoFHandler< dim, spacedim > &dof_handler, std::vector< std::vector< types::global_dof_index > > &dofs_per_block, std::vector< unsigned int > target_block={})
Definition: mg_tools.cc:1188
std::enable_if< IsBlockVector< VectorType >::value, unsignedint >::type n_blocks(const VectorType &vector)
Definition: operators.h:50
void swap(MemorySpaceData< Number, MemorySpace > &, MemorySpaceData< Number, MemorySpace > &)
VectorType::value_type * end(VectorType &V)
VectorType::value_type * begin(VectorType &V)
static const unsigned int invalid_unsigned_int
Definition: types.h:201
const types::global_dof_index invalid_dof_index
Definition: types.h:216