xref: /libCEED/examples/deal.II/bps.h (revision 2097acd54c344b4e8e24615cff43ae433aeb1497)
1 // ---------------------------------------------------------------------
2 //
3 // Copyright (C) 2023 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.
13 //
14 //  Authors: Peter Munch, Martin Kronbichler
15 //
16 // ---------------------------------------------------------------------
17 
18 // deal.II includes
19 #include <deal.II/dofs/dof_tools.h>
20 
21 #include <deal.II/fe/mapping.h>
22 
23 #include <deal.II/lac/la_parallel_vector.h>
24 
25 #include <deal.II/matrix_free/fe_evaluation.h>
26 #include <deal.II/matrix_free/matrix_free.h>
27 #include <deal.II/matrix_free/tools.h>
28 
29 // libCEED includes
30 #include <ceed.h>
31 #include <ceed/backend.h>
32 
33 // QFunction source
34 #include "bps-qfunctions.h"
35 
36 using namespace dealii;
37 
38 /**
39  * BP types. For more details, see https://ceed.exascaleproject.org/bps/.
40  */
41 enum class BPType : unsigned int
42 {
43   BP1,
44   BP2,
45   BP3,
46   BP4,
47   BP5,
48   BP6
49 };
50 
51 
52 
53 /**
54  * Struct storing relevant information regarding each BP.
55  */
56 struct BPInfo
57 {
58   BPInfo(const BPType type, const int dim, const int fe_degree)
59     : type(type)
60     , dim(dim)
61     , fe_degree(fe_degree)
62   {
63     if (type == BPType::BP1)
64       type_string = "BP1";
65     else if (type == BPType::BP2)
66       type_string = "BP2";
67     else if (type == BPType::BP3)
68       type_string = "BP3";
69     else if (type == BPType::BP4)
70       type_string = "BP4";
71     else if (type == BPType::BP5)
72       type_string = "BP5";
73     else if (type == BPType::BP6)
74       type_string = "BP6";
75 
76     this->n_q_points_1d = (type <= BPType::BP4) ? (fe_degree + 2) : (fe_degree + 1);
77 
78     this->n_components =
79       (type == BPType::BP1 || type == BPType::BP3 || type == BPType::BP5) ? 1 : dim;
80   }
81 
82 
83   BPType       type;
84   std::string  type_string;
85   unsigned int dim;
86   unsigned int fe_degree;
87   unsigned int n_q_points_1d;
88   unsigned int n_components;
89 };
90 
91 
92 
93 /**
94  * Base class of operators.
95  */
96 template <typename Number>
97 class OperatorBase
98 {
99 public:
100   /**
101    * deal.II vector type
102    */
103   using VectorType = LinearAlgebra::distributed::Vector<Number>;
104 
105   /**
106    * Initialize vector.
107    */
108   virtual void
109   reinit() = 0;
110 
111   /**
112    * Perform matrix-vector product
113    */
114   virtual void
115   vmult(VectorType &dst, const VectorType &src) const = 0;
116 
117   /**
118    * Initialize vector.
119    */
120   virtual void
121   initialize_dof_vector(VectorType &vec) const = 0;
122 
123   /**
124    * Compute inverse of diagonal.
125    */
126   virtual void
127   compute_inverse_diagonal(VectorType &diagonal) const = 0;
128 };
129 
130 
131 /**
132  * Operator implementation using libCEED.
133  */
134 template <int dim, typename Number>
135 class OperatorCeed : public OperatorBase<Number>
136 {
137 public:
138   using VectorType = typename OperatorBase<Number>::VectorType;
139 
140   /**
141    * Constructor.
142    */
143   OperatorCeed(const Mapping<dim>              &mapping,
144                const DoFHandler<dim>           &dof_handler,
145                const AffineConstraints<Number> &constraints,
146                const Quadrature<dim>           &quadrature,
147                const BPType                    &bp,
148                const std::string               &resource)
149     : mapping(mapping)
150     , dof_handler(dof_handler)
151     , constraints(constraints)
152     , quadrature(quadrature)
153     , bp(bp)
154     , resource(resource)
155   {
156     reinit();
157   }
158 
159   /**
160    * Destructor.
161    */
162   ~OperatorCeed()
163   {
164     CeedVectorDestroy(&src_ceed);
165     CeedVectorDestroy(&dst_ceed);
166     CeedOperatorDestroy(&op_apply);
167     CeedDestroy(&ceed);
168   }
169 
170   /**
171    * Initialized internal data structures, particularly, libCEED.
172    */
173   void
174   reinit() override
175   {
176     CeedVector           q_data;
177     CeedBasis            sol_basis;
178     CeedElemRestriction  sol_restriction;
179     CeedElemRestriction  q_data_restriction;
180     BuildContext         build_ctx_data;
181     CeedQFunctionContext build_ctx;
182     CeedQFunction        qf_apply;
183 
184     const auto &tria = dof_handler.get_triangulation();
185     const auto &fe   = dof_handler.get_fe();
186 
187     const auto n_components = fe.n_components();
188 
189     if (bp == BPType::BP1 || bp == BPType::BP3 || bp == BPType::BP5)
190       {
191         AssertThrow(n_components == 1, ExcInternalError());
192       }
193     else
194       {
195         AssertThrow(n_components == dim, ExcInternalError());
196       }
197 
198     // 1) create CEED instance -> "MatrixFree"
199     const char *ceed_spec = resource.c_str();
200     CeedInit(ceed_spec, &ceed);
201 
202     // 2) create shape functions -> "ShapeInfo"
203     const unsigned int fe_degree  = fe.tensor_degree();
204     const unsigned int n_q_points = quadrature.get_tensor_basis()[0].size();
205     CeedBasisCreateTensorH1Lagrange(
206       ceed, dim, n_components, fe_degree + 1, n_q_points, CEED_GAUSS, &sol_basis);
207 
208     // 3) create restriction matrix -> DoFInfo
209     unsigned int n_local_active_cells = 0;
210 
211     for (const auto &cell : dof_handler.active_cell_iterators())
212       if (cell->is_locally_owned())
213         n_local_active_cells++;
214 
215     partitioner =
216       std::make_shared<Utilities::MPI::Partitioner>(dof_handler.locally_owned_dofs(),
217                                                     DoFTools::extract_locally_active_dofs(
218                                                       dof_handler),
219                                                     dof_handler.get_communicator());
220 
221     std::vector<CeedInt> indices;
222     indices.reserve(n_local_active_cells * fe.n_dofs_per_cell() / n_components);
223 
224     const auto dof_mapping = FETools::lexicographic_to_hierarchic_numbering<dim>(fe_degree);
225 
226     std::vector<types::global_dof_index> local_indices(fe.n_dofs_per_cell());
227 
228     for (const auto &cell : dof_handler.active_cell_iterators())
229       if (cell->is_locally_owned())
230         {
231           cell->get_dof_indices(local_indices);
232 
233           for (const auto i : dof_mapping)
234             indices.emplace_back(
235               partitioner->global_to_local(local_indices[fe.component_to_system_index(0, i)]) /
236               n_components);
237         }
238 
239     CeedElemRestrictionCreate(ceed,
240                               n_local_active_cells,
241                               fe.n_dofs_per_cell() / n_components,
242                               n_components,
243                               std::max<unsigned int>(this->extended_local_size() / n_components, 1),
244                               this->extended_local_size(),
245                               CEED_MEM_HOST,
246                               CEED_COPY_VALUES,
247                               indices.data(),
248                               &sol_restriction);
249 
250     // 4) create mapping -> MappingInfo
251     const unsigned int n_components_metric = (bp <= BPType::BP2) ? 1 : (dim * (dim + 1) / 2);
252 
253     this->weights = compute_metric_data(ceed, mapping, tria, quadrature, bp);
254 
255     strides = {{1,
256                 static_cast<int>(quadrature.size()),
257                 static_cast<int>(quadrature.size() * n_components_metric)}};
258     CeedVectorCreate(ceed, weights.size(), &q_data);
259     CeedVectorSetArray(q_data, CEED_MEM_HOST, CEED_USE_POINTER, weights.data());
260     CeedElemRestrictionCreateStrided(ceed,
261                                      n_local_active_cells,
262                                      quadrature.size(),
263                                      n_components_metric,
264                                      weights.size(),
265                                      strides.data(),
266                                      &q_data_restriction);
267 
268     build_ctx_data.dim       = dim;
269     build_ctx_data.space_dim = dim;
270 
271     CeedQFunctionContextCreate(ceed, &build_ctx);
272     CeedQFunctionContextSetData(
273       build_ctx, CEED_MEM_HOST, CEED_COPY_VALUES, sizeof(build_ctx_data), &build_ctx_data);
274 
275     // 5) create q operation
276     if (bp == BPType::BP1)
277       CeedQFunctionCreateInterior(ceed, 1, f_apply_mass, f_apply_mass_loc, &qf_apply);
278     else if (bp == BPType::BP2)
279       CeedQFunctionCreateInterior(ceed, 1, f_apply_mass_vec, f_apply_mass_vec_loc, &qf_apply);
280     else if (bp == BPType::BP3 || bp == BPType::BP5)
281       CeedQFunctionCreateInterior(ceed, 1, f_apply_poisson, f_apply_poisson_loc, &qf_apply);
282     else if (bp == BPType::BP4 || bp == BPType::BP6)
283       CeedQFunctionCreateInterior(ceed, 1, f_apply_poisson_vec, f_apply_poisson_vec_loc, &qf_apply);
284     else
285       AssertThrow(false, ExcInternalError());
286 
287     if (bp <= BPType::BP2)
288       CeedQFunctionAddInput(qf_apply, "u", n_components, CEED_EVAL_INTERP);
289     else
290       CeedQFunctionAddInput(qf_apply, "u", dim * n_components, CEED_EVAL_GRAD);
291 
292     CeedQFunctionAddInput(qf_apply, "qdata", n_components_metric, CEED_EVAL_NONE);
293 
294     if (bp <= BPType::BP2)
295       CeedQFunctionAddOutput(qf_apply, "v", n_components, CEED_EVAL_INTERP);
296     else
297       CeedQFunctionAddOutput(qf_apply, "v", dim * n_components, CEED_EVAL_GRAD);
298 
299     CeedQFunctionSetContext(qf_apply, build_ctx);
300 
301     // 6) put everything together
302     CeedOperatorCreate(ceed, qf_apply, CEED_QFUNCTION_NONE, CEED_QFUNCTION_NONE, &op_apply);
303 
304     CeedOperatorSetField(op_apply, "u", sol_restriction, sol_basis, CEED_VECTOR_ACTIVE);
305     CeedOperatorSetField(op_apply, "qdata", q_data_restriction, CEED_BASIS_NONE, q_data);
306     CeedOperatorSetField(op_apply, "v", sol_restriction, sol_basis, CEED_VECTOR_ACTIVE);
307 
308     // 7) libCEED vectors
309     CeedElemRestrictionCreateVector(sol_restriction, &src_ceed, NULL);
310     CeedElemRestrictionCreateVector(sol_restriction, &dst_ceed, NULL);
311 
312     // 8) cleanup
313     CeedVectorDestroy(&q_data);
314     CeedElemRestrictionDestroy(&q_data_restriction);
315     CeedElemRestrictionDestroy(&sol_restriction);
316     CeedBasisDestroy(&sol_basis);
317     CeedQFunctionContextDestroy(&build_ctx);
318     CeedQFunctionDestroy(&qf_apply);
319   }
320 
321   /**
322    * Perform matrix-vector product.
323    */
324   void
325   vmult(VectorType &dst, const VectorType &src) const override
326   {
327     // communicate: update ghost values
328     src.update_ghost_values();
329 
330     if (dof_handler.get_fe().n_components() == 1)
331       {
332         // pass memory buffers to libCEED
333         VectorTypeCeed x(src_ceed);
334         VectorTypeCeed y(dst_ceed);
335         x.set_array(src);
336         y.set_array(dst);
337 
338         // apply operator
339         CeedOperatorApply(op_apply, x(), y(), CEED_REQUEST_IMMEDIATE);
340 
341         // pull arrays back to deal.II
342         x.sync_to_host();
343         y.sync_to_host();
344       }
345     else // TODO: needed for multiple components
346       {
347         // allocate space for block vectors
348         src_tmp.reinit(this->extended_local_size(), true);
349         dst_tmp.reinit(this->extended_local_size(), true);
350 
351         // copy to block vector
352         copy_to_block_vector(src_tmp, src);
353 
354         // pass memory buffers to libCEED
355         VectorTypeCeed x(src_ceed);
356         VectorTypeCeed y(dst_ceed);
357         x.set_array(src_tmp);
358         y.set_array(dst_tmp);
359 
360         // apply operator
361         CeedOperatorApply(op_apply, x(), y(), CEED_REQUEST_IMMEDIATE);
362 
363         // pull arrays back to deal.II
364         x.sync_to_host();
365         y.sync_to_host();
366 
367         // copy from block vector
368         copy_from_block_vector(dst, dst_tmp);
369       }
370 
371     // communicate: compress
372     src.zero_out_ghost_values();
373     dst.compress(VectorOperation::add);
374 
375     // apply constraints: we assume homogeneous DBC
376     constraints.set_zero(dst);
377   }
378 
379   /**
380    * Initialized vector.
381    */
382   void
383   initialize_dof_vector(VectorType &vec) const override
384   {
385     vec.reinit(partitioner);
386   }
387 
388   /**
389    * Compute inverse of diagonal.
390    */
391   void
392   compute_inverse_diagonal(VectorType &diagonal) const override
393   {
394     this->initialize_dof_vector(diagonal);
395 
396     // pass memory buffer to libCEED
397     VectorTypeCeed y(dst_ceed);
398     y.set_array(diagonal);
399 
400     CeedOperatorLinearAssembleDiagonal(op_apply, y(), CEED_REQUEST_IMMEDIATE);
401 
402     // pull array back to deal.II
403     y.sync_to_host();
404 
405     const unsigned int n_components = dof_handler.get_fe().n_components();
406 
407     if (n_components > 1) // TODO: needed for multiple components
408       {
409         VectorType tmp(diagonal);
410 
411         copy_from_block_vector(tmp, diagonal);
412 
413         std::swap(tmp, diagonal);
414       }
415 
416     diagonal.compress(VectorOperation::add);
417 
418     for (auto &i : diagonal)
419       i = (std::abs(i) > 1.0e-10) ? (1.0 / i) : 1.0;
420   }
421 
422 private:
423   /**
424    * Wrapper around a deal.II vector to create a libCEED vector view.
425    */
426   class VectorTypeCeed
427   {
428   public:
429     /**
430      * Constructor.
431      */
432     VectorTypeCeed(const CeedVector &vec_orig)
433     {
434       vec_ceed = NULL;
435       CeedVectorReferenceCopy(vec_orig, &vec_ceed);
436     }
437 
438     /**
439      * Return libCEED vector view.
440      */
441     CeedVector &
442     operator()()
443     {
444       return vec_ceed;
445     }
446 
447     /**
448      * Set deal.II memory in libCEED vector.
449      */
450     void
451     set_array(const VectorType &vec)
452     {
453       CeedVectorSetArray(vec_ceed, CEED_MEM_HOST, CEED_USE_POINTER, vec.get_values());
454     }
455 
456     /**
457      * Sync memory from device to host.
458      */
459     void
460     sync_to_host()
461     {
462       CeedVectorSyncArray(vec_ceed, CEED_MEM_HOST);
463     }
464 
465     /**
466      * Destructor: destroy vector view.
467      */
468     ~VectorTypeCeed()
469     {
470       bool has_array;
471       CeedVectorHasBorrowedArrayOfType(vec_ceed, CEED_MEM_HOST, &has_array);
472       if (has_array)
473         {
474           CeedScalar *ptr;
475           CeedVectorTakeArray(vec_ceed, CEED_MEM_HOST, &ptr);
476         }
477       CeedVectorDestroy(&vec_ceed);
478     }
479 
480   private:
481     /**
482      * libCEED vector view.
483      */
484     CeedVector vec_ceed;
485   };
486 
487   /**
488    * Copy from block vector.
489    *
490    * @note Only needed for multiple components.
491    */
492   void
493   copy_from_block_vector(VectorType &dst, const VectorType &src) const
494   {
495     const unsigned int scalar_size = this->extended_local_size() / dim;
496 
497     for (unsigned int i = 0; i < scalar_size; ++i)
498       for (unsigned int j = 0; j < dim; ++j)
499         dst.get_values()[j + i * dim] = src.get_values()[j * scalar_size + i];
500   }
501 
502   /**
503    * Copy to block vector.
504    *
505    * @note Only needed for multiple components.
506    */
507   void
508   copy_to_block_vector(VectorType &dst, const VectorType &src) const
509   {
510     const unsigned int scalar_size = this->extended_local_size() / dim;
511 
512     for (unsigned int i = 0; i < scalar_size; ++i)
513       for (unsigned int j = 0; j < dim; ++j)
514         dst.get_values()[j * scalar_size + i] = src.get_values()[j + i * dim];
515   }
516 
517   /**
518    * Number of locally active DoFs.
519    */
520   unsigned int
521   extended_local_size() const
522   {
523     return partitioner->locally_owned_size() + partitioner->n_ghost_indices();
524   }
525 
526   /**
527    * Compute metric data: Jacobian, ...
528    */
529   static std::vector<double>
530   compute_metric_data(const Ceed               &ceed,
531                       const Mapping<dim>       &mapping,
532                       const Triangulation<dim> &tria,
533                       const Quadrature<dim>    &quadrature,
534                       const BPType              bp)
535   {
536     std::vector<double> weights;
537 
538     if (false)
539       {
540         FE_Nothing<dim> dummy_fe;
541         FEValues<dim>   fe_values(mapping, dummy_fe, quadrature, update_JxW_values);
542 
543         for (const auto &cell : tria.active_cell_iterators())
544           if (cell->is_locally_owned())
545             {
546               fe_values.reinit(cell);
547 
548               for (const auto q : fe_values.quadrature_point_indices())
549                 weights.emplace_back(fe_values.JxW(q));
550             }
551 
552         return weights;
553       }
554 
555     CeedBasis            geo_basis;
556     CeedVector           q_data;
557     CeedElemRestriction  q_data_restriction;
558     CeedVector           node_coords;
559     CeedElemRestriction  geo_restriction;
560     CeedQFunctionContext build_ctx;
561     CeedQFunction        qf_build;
562     CeedOperator         op_build;
563 
564     const unsigned int n_q_points = quadrature.get_tensor_basis()[0].size();
565 
566     const unsigned int n_components = (bp <= BPType::BP2) ? 1 : (dim * (dim + 1) / 2);
567 
568     const auto mapping_q = dynamic_cast<const MappingQ<dim> *>(&mapping);
569 
570     AssertThrow(mapping_q, ExcMessage("Wrong mapping!"));
571 
572     const unsigned int fe_degree = mapping_q->get_degree();
573 
574     CeedBasisCreateTensorH1Lagrange(
575       ceed, dim, dim, fe_degree + 1, n_q_points, CEED_GAUSS, &geo_basis);
576 
577     unsigned int n_local_active_cells = 0;
578 
579     for (const auto &cell : tria.active_cell_iterators())
580       if (cell->is_locally_owned())
581         n_local_active_cells++;
582 
583     std::vector<double>  geo_support_points;
584     std::vector<CeedInt> geo_indices;
585 
586     FE_Q<dim> geo_fe(fe_degree);
587 
588     DoFHandler<dim> geo_dof_handler(tria);
589     geo_dof_handler.distribute_dofs(geo_fe);
590 
591     const auto geo_partitioner =
592       std::make_shared<Utilities::MPI::Partitioner>(geo_dof_handler.locally_owned_dofs(),
593                                                     DoFTools::extract_locally_active_dofs(
594                                                       geo_dof_handler),
595                                                     geo_dof_handler.get_communicator());
596 
597     geo_indices.reserve(n_local_active_cells * geo_fe.n_dofs_per_cell());
598 
599     const auto dof_mapping = FETools::lexicographic_to_hierarchic_numbering<dim>(fe_degree);
600 
601     FEValues<dim> fe_values(mapping,
602                             geo_fe,
603                             geo_fe.get_unit_support_points(),
604                             update_quadrature_points);
605 
606     std::vector<types::global_dof_index> local_indices(geo_fe.n_dofs_per_cell());
607 
608     const unsigned int n_points =
609       geo_partitioner->locally_owned_size() + geo_partitioner->n_ghost_indices();
610 
611     geo_support_points.resize(dim * n_points);
612 
613     for (const auto &cell : geo_dof_handler.active_cell_iterators())
614       if (cell->is_locally_owned())
615         {
616           fe_values.reinit(cell);
617           cell->get_dof_indices(local_indices);
618 
619           for (const auto i : dof_mapping)
620             {
621               const auto index = geo_partitioner->global_to_local(local_indices[i]);
622               geo_indices.emplace_back(index);
623 
624               const auto point = fe_values.quadrature_point(i);
625 
626               for (unsigned int d = 0; d < dim; ++d)
627                 geo_support_points[index + d * n_points] = point[d];
628             }
629         }
630 
631     weights.resize(n_local_active_cells * quadrature.size() * n_components);
632 
633     CeedInt strides[3] = {1,
634                           static_cast<int>(quadrature.size()),
635                           static_cast<int>(quadrature.size() * n_components)};
636 
637     CeedVectorCreate(ceed, weights.size(), &q_data);
638     CeedVectorSetArray(q_data, CEED_MEM_HOST, CEED_USE_POINTER, weights.data());
639     CeedElemRestrictionCreateStrided(ceed,
640                                      n_local_active_cells,
641                                      quadrature.size(),
642                                      n_components,
643                                      weights.size(),
644                                      strides,
645                                      &q_data_restriction);
646 
647     CeedVectorCreate(ceed, geo_support_points.size(), &node_coords);
648     CeedVectorSetArray(node_coords, CEED_MEM_HOST, CEED_USE_POINTER, geo_support_points.data());
649 
650     CeedElemRestrictionCreate(ceed,
651                               n_local_active_cells,
652                               geo_fe.n_dofs_per_cell(),
653                               dim,
654                               std::max<unsigned int>(geo_support_points.size() / dim, 1),
655                               geo_support_points.size(),
656                               CEED_MEM_HOST,
657                               CEED_COPY_VALUES,
658                               geo_indices.data(),
659                               &geo_restriction);
660 
661     BuildContext build_ctx_data;
662     build_ctx_data.dim       = dim;
663     build_ctx_data.space_dim = dim;
664 
665     CeedQFunctionContextCreate(ceed, &build_ctx);
666     CeedQFunctionContextSetData(
667       build_ctx, CEED_MEM_HOST, CEED_USE_POINTER, sizeof(build_ctx_data), &build_ctx_data);
668 
669     // 5) create q operation
670     if (bp <= BPType::BP2)
671       CeedQFunctionCreateInterior(ceed, 1, f_build_mass, f_build_mass_loc, &qf_build);
672     else
673       CeedQFunctionCreateInterior(ceed, 1, f_build_poisson, f_build_poisson_loc, &qf_build);
674 
675     CeedQFunctionAddInput(qf_build, "geo", dim * dim, CEED_EVAL_GRAD);
676     CeedQFunctionAddInput(qf_build, "weights", 1, CEED_EVAL_WEIGHT);
677     CeedQFunctionAddOutput(qf_build, "qdata", n_components, CEED_EVAL_NONE);
678     CeedQFunctionSetContext(qf_build, build_ctx);
679 
680     // 6) put everything together
681     CeedOperatorCreate(ceed, qf_build, CEED_QFUNCTION_NONE, CEED_QFUNCTION_NONE, &op_build);
682     CeedOperatorSetField(op_build, "geo", geo_restriction, geo_basis, CEED_VECTOR_ACTIVE);
683     CeedOperatorSetField(
684       op_build, "weights", CEED_ELEMRESTRICTION_NONE, geo_basis, CEED_VECTOR_NONE);
685     CeedOperatorSetField(
686       op_build, "qdata", q_data_restriction, CEED_BASIS_NONE, CEED_VECTOR_ACTIVE);
687 
688     CeedOperatorApply(op_build, node_coords, q_data, CEED_REQUEST_IMMEDIATE);
689 
690     CeedVectorDestroy(&node_coords);
691     CeedVectorSyncArray(q_data, CEED_MEM_HOST);
692     CeedVectorDestroy(&q_data);
693     CeedElemRestrictionDestroy(&geo_restriction);
694     CeedElemRestrictionDestroy(&q_data_restriction);
695     CeedBasisDestroy(&geo_basis);
696     CeedQFunctionContextDestroy(&build_ctx);
697     CeedQFunctionDestroy(&qf_build);
698     CeedOperatorDestroy(&op_build);
699 
700     return weights;
701   }
702 
703   /**
704    * Mapping object passed to the constructor.
705    */
706   const Mapping<dim> &mapping;
707 
708   /**
709    * DoFHandler object passed to the constructor.
710    */
711   const DoFHandler<dim> &dof_handler;
712 
713   /**
714    * Constraints object passed to the constructor.
715    */
716   const AffineConstraints<Number> &constraints;
717 
718   /**
719    * Quadrature rule object passed to the constructor.
720    */
721   const Quadrature<dim> &quadrature;
722 
723   /**
724    * Selected BP.
725    */
726   const BPType bp;
727 
728   /**
729    * Resource name.
730    */
731   const std::string resource;
732 
733   /**
734    * Partitioner for distributed vectors.
735    */
736   std::shared_ptr<Utilities::MPI::Partitioner> partitioner;
737 
738   /**
739    * libCEED data structures.
740    */
741   Ceed                   ceed;
742   std::vector<double>    weights;
743   std::array<CeedInt, 3> strides;
744   CeedVector             src_ceed;
745   CeedVector             dst_ceed;
746   CeedOperator           op_apply;
747 
748   /**
749    * Temporal (tempral) vectors.
750    *
751    * @note Only needed for multiple components.
752    */
753   mutable VectorType src_tmp;
754   mutable VectorType dst_tmp;
755 };
756 
757 
758 
759 template <int dim, typename Number>
760 class OperatorDealii : public OperatorBase<Number>
761 {
762 public:
763   using VectorType = typename OperatorBase<Number>::VectorType;
764 
765   /**
766    * Constructor.
767    */
768   OperatorDealii(const Mapping<dim>              &mapping,
769                  const DoFHandler<dim>           &dof_handler,
770                  const AffineConstraints<Number> &constraints,
771                  const Quadrature<dim>           &quadrature,
772                  const BPType                    &bp)
773     : mapping(mapping)
774     , dof_handler(dof_handler)
775     , constraints(constraints)
776     , quadrature(quadrature)
777     , bp(bp)
778   {
779     reinit();
780   }
781 
782   /**
783    * Destructor.
784    */
785   ~OperatorDealii() = default;
786 
787   /**
788    * Initialized internal data structures, particularly, MatrixFree.
789    */
790   void
791   reinit() override
792   {
793     // configure MatrixFree
794     typename MatrixFree<dim, Number>::AdditionalData additional_data;
795     additional_data.tasks_parallel_scheme =
796       MatrixFree<dim, Number>::AdditionalData::TasksParallelScheme::none;
797 
798     // create MatrixFree
799     matrix_free.reinit(mapping, dof_handler, constraints, quadrature, additional_data);
800   }
801 
802   /**
803    * Matrix-vector product.
804    */
805   void
806   vmult(VectorType &dst, const VectorType &src) const override
807   {
808     if (dof_handler.get_fe().n_components() == 1)
809       {
810         matrix_free.cell_loop(&OperatorDealii::do_cell_integral_range<1>, this, dst, src, true);
811       }
812     else
813       {
814         AssertThrow(dof_handler.get_fe().n_components() == dim, ExcInternalError());
815 
816         matrix_free.cell_loop(&OperatorDealii::do_cell_integral_range<dim>, this, dst, src, true);
817       }
818   }
819 
820   /**
821    * Initialize vector.
822    */
823   void
824   initialize_dof_vector(VectorType &vec) const override
825   {
826     matrix_free.initialize_dof_vector(vec);
827   }
828 
829   /**
830    * Compute inverse of diagonal.
831    */
832   void
833   compute_inverse_diagonal(VectorType &diagonal) const override
834   {
835     this->initialize_dof_vector(diagonal);
836 
837     if (dof_handler.get_fe().n_components() == 1)
838       {
839         MatrixFreeTools::compute_diagonal(matrix_free,
840                                           diagonal,
841                                           &OperatorDealii::do_cell_integral_local<1>,
842                                           this);
843       }
844     else
845       {
846         AssertThrow(dof_handler.get_fe().n_components() == dim, ExcInternalError());
847 
848         MatrixFreeTools::compute_diagonal(matrix_free,
849                                           diagonal,
850                                           &OperatorDealii::do_cell_integral_local<dim>,
851                                           this);
852       }
853 
854     for (auto &i : diagonal)
855       i = (std::abs(i) > 1.0e-10) ? (1.0 / i) : 1.0;
856   }
857 
858 private:
859   /**
860    * Cell integral without vector access.
861    */
862   template <int n_components>
863   void
864   do_cell_integral_local(FEEvaluation<dim, -1, 0, n_components, Number> &phi) const
865   {
866     if (bp <= BPType::BP2) // mass matrix
867       {
868         phi.evaluate(EvaluationFlags::values);
869         for (const auto q : phi.quadrature_point_indices())
870           phi.submit_value(phi.get_value(q), q);
871         phi.integrate(EvaluationFlags::values);
872       }
873     else // Poisson operator
874       {
875         phi.evaluate(EvaluationFlags::gradients);
876         for (const auto q : phi.quadrature_point_indices())
877           phi.submit_gradient(phi.get_gradient(q), q);
878         phi.integrate(EvaluationFlags::gradients);
879       }
880   }
881 
882   /**
883    * Cell integral on a range of cells.
884    */
885   template <int n_components>
886   void
887   do_cell_integral_range(const MatrixFree<dim, Number>               &matrix_free,
888                          VectorType                                  &dst,
889                          const VectorType                            &src,
890                          const std::pair<unsigned int, unsigned int> &range) const
891   {
892     FEEvaluation<dim, -1, 0, n_components, Number> phi(matrix_free, range);
893 
894     for (unsigned cell = range.first; cell < range.second; ++cell)
895       {
896         phi.reinit(cell);
897         phi.read_dof_values(src);            // read source vector
898         do_cell_integral_local(phi);         // cell integral
899         phi.distribute_local_to_global(dst); // write to destination vector
900       }
901   }
902 
903   /**
904    * Mapping object passed to the constructor.
905    */
906   const Mapping<dim> &mapping;
907 
908   /**
909    * DoFHandler object passed to the constructor.
910    */
911   const DoFHandler<dim> &dof_handler;
912 
913   /**
914    * Constraints object passed to the constructor.
915    */
916   const AffineConstraints<Number> &constraints;
917 
918   /**
919    * Quadrature rule object passed to the constructor.
920    */
921   const Quadrature<dim> &quadrature;
922 
923   /**
924    * Selected BP.
925    */
926   const BPType bp;
927 
928   /**
929    * MatrixFree object.
930    */
931   MatrixFree<dim, Number> matrix_free;
932 };
933