DOLFIN-X
DOLFIN-X C++ interface
evaluate.h
1 // Copyright (C) 2020 Jack S. Hale
2 //
3 // This file is part of DOLFINX (https://www.fenicsproject.org)
4 //
5 // SPDX-License-Identifier: LGPL-3.0-or-later
6 //
7 
8 #pragma once
9 
10 #include <dolfinx/common/array2d.h>
11 #include <dolfinx/common/span.hpp>
12 #include <dolfinx/fem/utils.h>
13 #include <dolfinx/mesh/Mesh.h>
14 #include <vector>
15 
16 namespace dolfinx::fem
17 {
18 
19 template <typename T>
20 class Expression;
21 
27 template <typename T>
28 void eval(array2d<T>& values, const fem::Expression<T>& e,
29  const tcb::span<const std::int32_t>& active_cells)
30 {
31  // Extract data from Expression
32  auto mesh = e.mesh();
33  assert(mesh);
34 
35  // Prepare coefficients
37 
38  // Prepare constants
39  const std::vector<T> constant_values = dolfinx::fem::pack_constants(e);
40 
41  const auto& fn = e.get_tabulate_expression();
42 
43  // Prepare cell geometry
45  = mesh->geometry().dofmap();
46  const fem::CoordinateElement& cmap = mesh->geometry().cmap();
47 
48  // Prepate cell permutation info
49  mesh->topology_mutable().create_entity_permutations();
50  const std::vector<std::uint32_t>& cell_info
51  = mesh->topology().get_cell_permutation_info();
52 
53  // FIXME: Add proper interface for num coordinate dofs
54  const int num_dofs_g = x_dofmap.num_links(0);
55  const array2d<double>& x_g = mesh->geometry().x();
56 
57  // Create data structures used in evaluation
58  const int gdim = mesh->geometry().dim();
59  array2d<double> coordinate_dofs(num_dofs_g, gdim);
60 
61  // Iterate over cells and 'assemble' into values
62  std::vector<T> values_e(e.num_points() * e.value_size(), 0);
63  for (std::size_t i = 0; i < active_cells.size(); ++i)
64  {
65  const std::int32_t c = active_cells[i];
66  auto x_dofs = x_dofmap.links(c);
67  for (int j = 0; j < num_dofs_g; ++j)
68  {
69  const auto x_dof = x_dofs[j];
70  for (int k = 0; k < gdim; ++k)
71  coordinate_dofs(j, k) = x_g(x_dof, k);
72  }
73 
74  auto coeff_cell = coeffs.row(c);
75  std::fill(values_e.begin(), values_e.end(), 0.0);
76  fn(values_e.data(), coeff_cell.data(), constant_values.data(),
77  coordinate_dofs.data());
78 
79  for (std::size_t j = 0; j < values_e.size(); ++j)
80  values(i, j) = values_e[j];
81  }
82 }
83 
84 } // namespace dolfinx::fem
This class provides a dynamic 2-dimensional row-wise array data structure.
Definition: array2d.h:21
constexpr tcb::span< value_type > row(size_type i)
Access a row in the array.
Definition: array2d.h:116
constexpr value_type * data() noexcept
Get pointer to the first element of the underlying storage.
Definition: array2d.h:133
This class manages coordinate mappings for isoparametric cells.
Definition: CoordinateElement.h:31
Represents a mathematical expression evaluated at a pre-defined set of points on the reference cell....
Definition: Expression.h:39
const std::size_t value_size() const
Get value size.
Definition: Expression.h:128
std::shared_ptr< const mesh::Mesh > mesh() const
Get mesh.
Definition: Expression.h:120
const std::size_t num_points() const
Get number of points.
Definition: Expression.h:132
const std::function< void(T *, const T *, const T *, const double *)> & get_tabulate_expression() const
Get function for tabulate_expression.
Definition: Expression.h:104
This class provides a static adjacency list data structure. It is commonly used to store directed gra...
Definition: AdjacencyList.h:68
tcb::span< T > links(int node)
Get the links (edges) for given node.
Definition: AdjacencyList.h:151
int num_links(int node) const
Number of connections for given node.
Definition: AdjacencyList.h:141
Finite element method functionality.
Definition: assemble_matrix_impl.h:23
std::vector< typename U::scalar_type > pack_constants(const U &u)
Pack constants of u of generic type U ready for assembly.
Definition: utils.h:453
void eval(array2d< T > &values, const fem::Expression< T > &e, const tcb::span< const std::int32_t > &active_cells)
Evaluate a UFC expression.
Definition: evaluate.h:28
array2d< typename U::scalar_type > pack_coefficients(const U &u)
Pack coefficients of u of generic type U ready for assembly.
Definition: utils.h:398