DOLFINx 0.10.0.0
DOLFINx C++ interface
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DirichletBC.h
1// Copyright (C) 2007-2024 Michal Habera, Anders Logg, Garth N. Wells, Jørgen
2// S.Dokken and Paul T. Kühner
3//
4// This file is part of DOLFINx (https://www.fenicsproject.org)
5//
6// SPDX-License-Identifier: LGPL-3.0-or-later
7
8#pragma once
9
10#include "Constant.h"
11#include "DofMap.h"
12#include "Function.h"
13#include "FunctionSpace.h"
14#include <algorithm>
15#include <array>
16#include <concepts>
17#include <dolfinx/common/types.h>
18#include <functional>
19#include <memory>
20#include <optional>
21#include <span>
22#include <type_traits>
23#include <utility>
24#include <variant>
25#include <vector>
26
27namespace dolfinx::fem
28{
29
55std::vector<std::int32_t>
56locate_dofs_topological(const mesh::Topology& topology, const DofMap& dofmap,
57 int dim, std::span<const std::int32_t> entities,
58 bool remote = true);
59
86std::array<std::vector<std::int32_t>, 2> locate_dofs_topological(
87 const mesh::Topology& topology,
88 std::array<std::reference_wrapper<const DofMap>, 2> dofmaps, int dim,
89 std::span<const std::int32_t> entities, bool remote = true);
90
102template <std::floating_point T, typename U>
103std::vector<std::int32_t> locate_dofs_geometrical(const FunctionSpace<T>& V,
104 U marker_fn)
105{
106 // FIXME: Calling V.tabulate_dof_coordinates() is very expensive,
107 // especially when we usually want the boundary dofs only. Add
108 // interface that computes dofs coordinates only for specified cell.
109
110 assert(V.element());
111 if (V.element()->is_mixed())
112 {
113 throw std::runtime_error(
114 "Cannot locate dofs geometrically for mixed space. Use subspaces.");
115 }
116
117 // Compute dof coordinates
118 const std::vector<T> dof_coordinates = V.tabulate_dof_coordinates(true);
119
120 using cmdspan3x_t
121 = md::mdspan<const T, md::extents<std::size_t, 3, md::dynamic_extent>>;
122
123 // Compute marker for each dof coordinate
124 cmdspan3x_t x(dof_coordinates.data(), 3, dof_coordinates.size() / 3);
125 const std::vector<std::int8_t> marked_dofs = marker_fn(x);
126
127 std::vector<std::int32_t> dofs;
128 dofs.reserve(std::count(marked_dofs.begin(), marked_dofs.end(), true));
129 for (std::size_t i = 0; i < marked_dofs.size(); ++i)
130 {
131 if (marked_dofs[i])
132 dofs.push_back(i);
133 }
134
135 return dofs;
136}
137
151template <std::floating_point T, typename U>
152std::array<std::vector<std::int32_t>, 2> locate_dofs_geometrical(
153 const std::array<std::reference_wrapper<const FunctionSpace<T>>, 2>& V,
154 U marker_fn)
155{
156 // FIXME: Calling V.tabulate_dof_coordinates() is very expensive,
157 // especially when we usually want the boundary dofs only. Add
158 // interface that computes dofs coordinates only for specified cell.
159
160 // Get function spaces
161 const FunctionSpace<T>& V0 = V.at(0).get();
162 const FunctionSpace<T>& V1 = V.at(1).get();
163
164 // Get mesh
165 auto mesh = V0.mesh();
166 assert(mesh);
167 assert(V1.mesh());
168 if (mesh != V1.mesh())
169 throw std::runtime_error("Meshes are not the same.");
170 const int tdim = mesh->topology()->dim();
171
172 assert(V0.element());
173 assert(V1.element());
174 if (*V0.element() != *V1.element())
175 throw std::runtime_error("Function spaces must have the same element.");
176
177 // Compute dof coordinates
178 const std::vector<T> dof_coordinates = V1.tabulate_dof_coordinates(true);
179
180 using cmdspan3x_t
181 = md::mdspan<const T, md::extents<std::size_t, 3, md::dynamic_extent>>;
182
183 // Evaluate marker for each dof coordinate
184 cmdspan3x_t x(dof_coordinates.data(), 3, dof_coordinates.size() / 3);
185 const std::vector<std::int8_t> marked_dofs = marker_fn(x);
186
187 // Get dofmaps
188 std::shared_ptr<const DofMap> dofmap0 = V0.dofmap();
189 assert(dofmap0);
190 const int bs0 = dofmap0->bs();
191 std::shared_ptr<const DofMap> dofmap1 = V1.dofmap();
192 assert(dofmap1);
193 const int bs1 = dofmap1->bs();
194
195 const int element_bs = dofmap0->element_dof_layout().block_size();
196 assert(element_bs == dofmap1->element_dof_layout().block_size());
197
198 // Iterate over cells
199 auto topology = mesh->topology();
200 assert(topology);
201 std::vector<std::array<std::int32_t, 2>> bc_dofs;
202 for (int c = 0; c < topology->connectivity(tdim, 0)->num_nodes(); ++c)
203 {
204 // Get cell dofmaps
205 auto cell_dofs0 = dofmap0->cell_dofs(c);
206 auto cell_dofs1 = dofmap1->cell_dofs(c);
207
208 // Loop over cell dofs and add to bc_dofs if marked.
209 for (std::size_t i = 0; i < cell_dofs1.size(); ++i)
210 {
211 if (marked_dofs[cell_dofs1[i]])
212 {
213 // Unroll over blocks
214 for (int k = 0; k < element_bs; ++k)
215 {
216 const int local_pos = element_bs * i + k;
217 const std::div_t pos0 = std::div(local_pos, bs0);
218 const std::div_t pos1 = std::div(local_pos, bs1);
219 const std::int32_t dof_index0
220 = bs0 * cell_dofs0[pos0.quot] + pos0.rem;
221 const std::int32_t dof_index1
222 = bs1 * cell_dofs1[pos1.quot] + pos1.rem;
223 bc_dofs.push_back({dof_index0, dof_index1});
224 }
225 }
226 }
227 }
228
229 // Remove duplicates
230 std::ranges::sort(bc_dofs);
231 auto [unique_end, range_end] = std::ranges::unique(bc_dofs);
232 bc_dofs.erase(unique_end, range_end);
233
234 // Copy to separate array
235 std::array dofs = {std::vector<std::int32_t>(bc_dofs.size()),
236 std::vector<std::int32_t>(bc_dofs.size())};
237 std::ranges::transform(bc_dofs, dofs[0].begin(),
238 [](auto dof) { return dof[0]; });
239 std::ranges::transform(bc_dofs, dofs[1].begin(),
240 [](auto dof) { return dof[1]; });
241
242 return dofs;
243}
244
253template <dolfinx::scalar T, std::floating_point U = dolfinx::scalar_value_t<T>>
255{
256private:
259 std::size_t num_owned(const DofMap& dofmap,
260 std::span<const std::int32_t> dofs)
261 {
262 int bs = dofmap.index_map_bs();
263 std::int32_t map_size = dofmap.index_map->size_local();
264 std::int32_t owned_size = bs * map_size;
265 auto it = std::ranges::lower_bound(dofs, owned_size);
266 return std::distance(dofs.begin(), it);
267 }
268
270 static std::vector<std::int32_t>
271 unroll_dofs(std::span<const std::int32_t> dofs, int bs)
272 {
273 std::vector<std::int32_t> dofs_unrolled(bs * dofs.size());
274 for (std::size_t i = 0; i < dofs.size(); ++i)
275 for (int k = 0; k < bs; ++k)
276 dofs_unrolled[bs * i + k] = bs * dofs[i] + k;
277 return dofs_unrolled;
278 }
279
280public:
298 template <typename S, typename X>
299 requires(std::is_convertible_v<S, T>
300 || std::is_convertible_v<S, std::span<const T>>)
301 && std::is_convertible_v<std::remove_cvref_t<X>,
302 std::vector<std::int32_t>>
303 DirichletBC(const S& g, X&& dofs, std::shared_ptr<const FunctionSpace<U>> V)
304 : DirichletBC(std::make_shared<Constant<T>>(g), dofs, V)
305 {
306 }
307
323 template <typename X>
324 requires std::is_convertible_v<std::remove_cvref_t<X>,
325 std::vector<std::int32_t>>
326 DirichletBC(std::shared_ptr<const Constant<T>> g, X&& dofs,
327 std::shared_ptr<const FunctionSpace<U>> V)
328 : _function_space(V), _g(g), _dofs0(std::forward<X>(dofs)),
329 _owned_indices0(num_owned(*V->dofmap(), _dofs0))
330 {
331 assert(g);
332 assert(V);
333 if (g->shape.size() != V->element()->value_shape().size())
334 {
335 throw std::runtime_error(
336 "Rank mismatch between Constant and function space in DirichletBC");
337 }
338
339 if (g->value.size() != (std::size_t)_function_space->dofmap()->bs())
340 {
341 throw std::runtime_error(
342 "Creating a DirichletBC using a Constant is not supported when the "
343 "Constant size is not equal to the block size of the constrained "
344 "(sub-)space. Use a fem::Function to create the fem::DirichletBC.");
345 }
346
347 if (!V->element()->interpolation_ident())
348 {
349 throw std::runtime_error(
350 "Constant can be used only with point-evaluation elements");
351 }
352
353 // Unroll _dofs0 if dofmap block size > 1
354 if (const int bs = V->dofmap()->bs(); bs > 1)
355 {
356 _owned_indices0 *= bs;
357 _dofs0 = unroll_dofs(_dofs0, bs);
358 }
359 }
360
373 template <typename X>
374 requires std::is_convertible_v<std::remove_cvref_t<X>,
375 std::vector<std::int32_t>>
376 DirichletBC(std::shared_ptr<const Function<T, U>> g, X&& dofs)
377 : _function_space(g->function_space()), _g(g),
378 _dofs0(std::forward<X>(dofs)),
379 _owned_indices0(num_owned(*_function_space->dofmap(), _dofs0))
380 {
381 assert(_function_space);
382
383 // Unroll _dofs0 if dofmap block size > 1
384 if (const int bs = _function_space->dofmap()->bs(); bs > 1)
385 {
386 _owned_indices0 *= bs;
387 _dofs0 = unroll_dofs(_dofs0, bs);
388 }
389 }
390
412 template <typename X>
413 DirichletBC(std::shared_ptr<const Function<T, U>> g, X&& V_g_dofs,
414 std::shared_ptr<const FunctionSpace<U>> V)
415 : _function_space(V), _g(g),
416 _dofs0(std::forward<typename std::remove_reference_t<X>::value_type>(
417 V_g_dofs[0])),
418 _dofs1_g(std::forward<typename std::remove_reference_t<X>::value_type>(
419 V_g_dofs[1])),
420 _owned_indices0(num_owned(*_function_space->dofmap(), _dofs0))
421 {
422 }
423
426 DirichletBC(const DirichletBC& bc) = default;
427
430 DirichletBC(DirichletBC&& bc) = default;
431
433 ~DirichletBC() = default;
434
437 DirichletBC& operator=(const DirichletBC& bc) = default;
438
441
444 std::shared_ptr<const FunctionSpace<U>> function_space() const
445 {
446 return _function_space;
447 }
448
451 std::variant<std::shared_ptr<const Function<T, U>>,
452 std::shared_ptr<const Constant<T>>>
453 value() const
454 {
455 return _g;
456 }
457
464 std::pair<std::span<const std::int32_t>, std::int32_t> dof_indices() const
465 {
466 return {_dofs0, _owned_indices0};
467 }
468
491 void set(std::span<T> x, std::optional<std::span<const T>> x0,
492 T alpha = 1) const
493 {
494 // set_fn is a lambda which gets evaluated for every index in [0,
495 // _dofs0.size()) and its result is assigned to x[_dofs0[i]].
496 auto apply = [&](std::invocable<std::int32_t> auto set_fn)
497 {
498 static_assert(
499 std::is_same_v<std::invoke_result_t<decltype(set_fn), std::int32_t>,
500 T>);
501
502 std::int32_t x_size = x.size();
503 for (std::size_t i = 0; i < _dofs0.size(); ++i)
504 {
505 if (_dofs0[i] < x_size)
506 x[_dofs0[i]] = set_fn(i);
507 }
508 };
509
510 if (alpha == T(0)) // Optimisation for when alpha == 0
511 {
512 apply([](std::int32_t) -> T { return 0; });
513 return;
514 }
515
516 if (std::holds_alternative<std::shared_ptr<const Function<T, U>>>(_g))
517 {
518 auto g = std::get<std::shared_ptr<const Function<T, U>>>(_g);
519 assert(g);
520 std::span<const T> values = g->x()->array();
521
522 // Extract degrees of freedom associated with g. If g is in a collapsed
523 // sub-space, get the dofs in this space, otherwise the degrees of g is
524 // the same as for x
525 auto dofs_g = _dofs1_g.empty() ? std::span(_dofs0) : std::span(_dofs1_g);
526
527 if (x0)
528 {
529 assert(x.size() <= x0->size());
530 apply(
531 [dofs_g, x0 = *x0, alpha, values,
532 &dofs0 = this->_dofs0](std::int32_t i) -> T
533 {
534 assert(dofs_g[i] < static_cast<std::int32_t>(values.size()));
535 return alpha * (values[dofs_g[i]] - x0[dofs0[i]]);
536 });
537 }
538 else
539 {
540 apply(
541 [dofs_g, values, alpha](std::int32_t i) -> T
542 {
543 assert(dofs_g[i] < static_cast<std::int32_t>(values.size()));
544 return alpha * values[dofs_g[i]];
545 });
546 }
547 }
548 else if (std::holds_alternative<std::shared_ptr<const Constant<T>>>(_g))
549 {
550 auto g = std::get<std::shared_ptr<const Constant<T>>>(_g);
551 const std::vector<T>& value = g->value;
552 std::int32_t bs = _function_space->dofmap()->bs();
553 if (x0)
554 {
555 assert(x.size() <= x0->size());
556 apply(
557 [x0 = *x0, alpha, bs, &value, &dofs0 = _dofs0](std::int32_t i) -> T
558 {
559 auto dof = dofs0[i];
560 return alpha * (value[dof % bs] - x0[dof]);
561 });
562 }
563 else
564 {
565 apply([alpha, bs, &value, &dofs0 = _dofs0](std::int32_t i) -> T
566 { return alpha * value[dofs0[i] % bs]; });
567 }
568 }
569 else
570 {
571 // replace with std::unreachable once C++23 is supported
572 assert(false);
573 }
574 }
575
585 void mark_dofs(std::span<std::int8_t> markers) const
586 {
587 for (std::int32_t idx : _dofs0)
588 {
589 assert(idx < (std::int32_t)markers.size());
590 markers[idx] = true;
591 }
592 }
593
594private:
595 // The function space (possibly a sub function space)
596 std::shared_ptr<const FunctionSpace<U>> _function_space;
597
598 // The function
599 std::variant<std::shared_ptr<const Function<T, U>>,
600 std::shared_ptr<const Constant<T>>>
601 _g;
602
603 // Dof indices (_dofs0) in _function_space and (_dofs1_g) in the space
604 // of _g. _dofs1_g may be empty if _dofs0 can be re-used
605 std::vector<std::int32_t> _dofs0, _dofs1_g;
606
607 // The first _owned_indices in _dofs are owned by this process
608 std::int32_t _owned_indices0 = -1;
609};
610} // namespace dolfinx::fem
Degree-of-freedom map representations and tools.
Constant value which can be attached to a Form.
Definition Constant.h:23
DirichletBC(const S &g, X &&dofs, std::shared_ptr< const FunctionSpace< U > > V)
Create a representation of a Dirichlet boundary condition constrained by a scalar- or vector-valued c...
Definition DirichletBC.h:303
DirichletBC & operator=(const DirichletBC &bc)=default
DirichletBC(std::shared_ptr< const Constant< T > > g, X &&dofs, std::shared_ptr< const FunctionSpace< U > > V)
Create a representation of a Dirichlet boundary condition constrained by a fem::Constant.
Definition DirichletBC.h:326
void set(std::span< T > x, std::optional< std::span< const T > > x0, T alpha=1) const
Set entries in an array that are constrained by Dirichlet boundary conditions.
Definition DirichletBC.h:491
std::variant< std::shared_ptr< const Function< T, U > >, std::shared_ptr< const Constant< T > > > value() const
Definition DirichletBC.h:453
DirichletBC(const DirichletBC &bc)=default
DirichletBC(DirichletBC &&bc)=default
std::pair< std::span< const std::int32_t >, std::int32_t > dof_indices() const
Definition DirichletBC.h:464
std::shared_ptr< const FunctionSpace< U > > function_space() const
Definition DirichletBC.h:444
~DirichletBC()=default
Destructor.
DirichletBC(std::shared_ptr< const Function< T, U > > g, X &&dofs)
Create a representation of a Dirichlet boundary condition where the space being constrained is the sa...
Definition DirichletBC.h:376
DirichletBC & operator=(DirichletBC &&bc)=default
Move assignment operator.
void mark_dofs(std::span< std::int8_t > markers) const
Set markers[i] = true if dof i has a boundary condition applied.
Definition DirichletBC.h:585
DirichletBC(std::shared_ptr< const Function< T, U > > g, X &&V_g_dofs, std::shared_ptr< const FunctionSpace< U > > V)
Create a representation of a Dirichlet boundary condition where the space being constrained and the f...
Definition DirichletBC.h:413
Degree-of-freedom map.
Definition DofMap.h:73
std::shared_ptr< const common::IndexMap > index_map
Index map that describes the parallel distribution of the dofmap.
Definition DofMap.h:164
int index_map_bs() const
Block size associated with the index_map.
Definition DofMap.cpp:276
This class represents a finite element function space defined by a mesh, a finite element,...
Definition FunctionSpace.h:34
std::shared_ptr< const DofMap > dofmap() const
The dofmap.
Definition FunctionSpace.h:361
std::shared_ptr< const mesh::Mesh< geometry_type > > mesh() const
The mesh.
Definition FunctionSpace.h:336
std::shared_ptr< const FiniteElement< geometry_type > > element() const
The finite element.
Definition FunctionSpace.h:342
std::vector< geometry_type > tabulate_dof_coordinates(bool transpose) const
Tabulate the physical coordinates of all dofs on this process.
Definition FunctionSpace.h:208
Definition Function.h:47
Finite element method functionality.
Definition assemble_expression_impl.h:23
std::vector< std::int32_t > locate_dofs_geometrical(const FunctionSpace< T > &V, U marker_fn)
Find degrees of freedom whose geometric coordinate is true for the provided marking function.
Definition DirichletBC.h:103
std::vector< std::int32_t > locate_dofs_topological(const mesh::Topology &topology, const DofMap &dofmap, int dim, std::span< const std::int32_t > entities, bool remote=true)
Find degrees-of-freedom which belong to the provided mesh entities (topological).
Definition DirichletBC.cpp:187
Mesh data structures and algorithms on meshes.
Definition DofMap.h:32