Reference documentation for deal.II version Git fff2869c79 2020-01-20 12:00:24 -0500
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dof_accessor_get.cc
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5 // This file is part of the deal.II library.
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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 #include <deal.II/dofs/dof_accessor.h>
17 #include <deal.II/dofs/dof_handler.h>
18 #include <deal.II/dofs/dof_levels.h>
19 
20 #include <deal.II/fe/fe.h>
21 
22 #include <deal.II/grid/tria_iterator.h>
23 #include <deal.II/grid/tria_iterator.templates.h>
24 
25 #include <deal.II/hp/dof_handler.h>
26 
27 #include <deal.II/lac/block_vector.h>
28 #include <deal.II/lac/la_parallel_block_vector.h>
29 #include <deal.II/lac/la_parallel_vector.h>
30 #include <deal.II/lac/la_vector.h>
31 #include <deal.II/lac/petsc_block_vector.h>
32 #include <deal.II/lac/petsc_vector.h>
33 #include <deal.II/lac/sparse_matrix.h>
34 #include <deal.II/lac/trilinos_epetra_vector.h>
35 #include <deal.II/lac/trilinos_parallel_block_vector.h>
36 #include <deal.II/lac/trilinos_tpetra_vector.h>
37 #include <deal.II/lac/trilinos_vector.h>
38 #include <deal.II/lac/vector.h>
39 
40 #include <vector>
41 
42 DEAL_II_NAMESPACE_OPEN
43 
44 
45 template <typename DoFHandlerType, bool lda>
46 template <class InputVector, typename number>
47 void
49  const InputVector &values,
50  Vector<number> & interpolated_values,
51  const unsigned int fe_index) const
52 {
53  if (this->is_active())
54  // If this cell is active: simply return the exact values on this
55  // cell unless the finite element we need to interpolate to is different
56  // than the one we have on the current cell
57  {
58  if ((dynamic_cast<DoFHandler<DoFHandlerType::dimension,
59  DoFHandlerType::space_dimension> *>(
60  this->dof_handler) != nullptr) ||
61  // for hp-DoFHandlers, we need to require that on
62  // active cells, you either don't specify an fe_index,
63  // or that you specify the correct one
64  (fe_index == this->active_fe_index()) ||
65  (fe_index == DoFHandlerType::default_fe_index))
66  this->get_dof_values(values, interpolated_values);
67  else
68  {
69  // well, here we need to first get the values from the current
70  // cell and then interpolate it to the element requested. this
71  // can clearly only happen for hp::DoFHandler objects
72  const unsigned int dofs_per_cell = this->get_fe().dofs_per_cell;
73  if (dofs_per_cell == 0)
74  {
75  interpolated_values = 0;
76  }
77  else
78  {
79  Vector<number> tmp(dofs_per_cell);
80  this->get_dof_values(values, tmp);
81 
82  FullMatrix<double> interpolation(
83  this->dof_handler->get_fe(fe_index).dofs_per_cell,
84  this->get_fe().dofs_per_cell);
85  this->dof_handler->get_fe(fe_index).get_interpolation_matrix(
86  this->get_fe(), interpolation);
87  interpolation.vmult(interpolated_values, tmp);
88  }
89  }
90  }
91  else
92  // The cell is not active; we need to obtain data them from
93  // children recursively.
94  {
95  // we are on a non-active cell. these do not have any finite
96  // element associated with them in the hp context (in the non-hp
97  // context, we can simply assume that the FE space to which we
98  // want to interpolate is the same as for all elements in the
99  // mesh). consequently, we cannot interpolate from children's FE
100  // space to this cell's (unknown) FE space unless an explicit
101  // fe_index is given
102  Assert((dynamic_cast<DoFHandler<DoFHandlerType::dimension,
103  DoFHandlerType::space_dimension> *>(
104  this->dof_handler) != nullptr) ||
105  (fe_index != DoFHandlerType::default_fe_index),
106  ExcMessage(
107  "You cannot call this function on non-active cells "
108  "of hp::DoFHandler objects unless you provide an explicit "
109  "finite element index because they do not have naturally "
110  "associated finite element spaces associated: degrees "
111  "of freedom are only distributed on active cells for which "
112  "the active_fe_index has been set."));
113 
114  const FiniteElement<dim, spacedim> &fe =
115  this->get_dof_handler().get_fe(fe_index);
116  const unsigned int dofs_per_cell = fe.dofs_per_cell;
117 
118  Assert(this->dof_handler != nullptr,
119  typename BaseClass::ExcInvalidObject());
120  Assert(interpolated_values.size() == dofs_per_cell,
121  typename BaseClass::ExcVectorDoesNotMatch());
122  Assert(values.size() == this->dof_handler->n_dofs(),
123  typename BaseClass::ExcVectorDoesNotMatch());
124 
125 
126  // see if the finite element we have on the current cell has any
127  // degrees of freedom to begin with; if not (e.g., when
128  // interpolating FE_Nothing), then simply skip all of the
129  // following since the output vector would be of size zero
130  // anyway (and in fact is of size zero, see the assertion above)
131  if (fe.dofs_per_cell > 0)
132  {
133  Vector<number> tmp1(dofs_per_cell);
134  Vector<number> tmp2(dofs_per_cell);
135 
136  interpolated_values = 0;
137 
138  // later on we will have to push the values interpolated from the
139  // child to the mother cell into the output vector. unfortunately,
140  // there are two types of elements: ones where you add up the
141  // contributions from the different child cells, and ones where you
142  // overwrite.
143  //
144  // an example for the first is piecewise constant (and discontinuous)
145  // elements, where we build the value on the coarse cell by averaging
146  // the values from the cell (i.e. by adding up a fraction of the
147  // values of their values)
148  //
149  // an example for the latter are the usual continuous elements. the
150  // value on a vertex of a coarse cell must there be the same,
151  // irrespective of the adjacent cell we are presently on. so we always
152  // overwrite. in fact, we must, since we cannot know in advance how
153  // many neighbors there will be, so there is no way to compute the
154  // average with fixed factors
155  //
156  // so we have to find out to which type this element belongs. the
157  // difficulty is: the finite element may be a composed one, so we can
158  // only hope to do this for each shape function individually. in fact,
159  // there are even weird finite elements (for example the
160  // Raviart-Thomas element) which have shape functions that are
161  // additive (interior ones) and others that are overwriting (face
162  // degrees of freedom that need to be continuous across the face).
163  for (unsigned int child = 0; child < this->n_children(); ++child)
164  {
165  // get the values from the present child, if necessary by
166  // interpolation itself either from its own children or
167  // by interpolating from the finite element on an active
168  // child to the finite element space requested here
169  this->child(child)->get_interpolated_dof_values(values,
170  tmp1,
171  fe_index);
172  // interpolate these to the mother cell
173  fe.get_restriction_matrix(child, this->refinement_case())
174  .vmult(tmp2, tmp1);
175 
176  // and add up or set them in the output vector
177  for (unsigned int i = 0; i < dofs_per_cell; ++i)
178  if (fe.restriction_is_additive(i))
179  interpolated_values(i) += tmp2(i);
180  else if (tmp2(i) != number())
181  interpolated_values(i) = tmp2(i);
182  }
183  }
184  }
185 }
186 
187 
188 // --------------------------------------------------------------------------
189 // explicit instantiations
190 #include "dof_accessor_get.inst"
191 
192 DEAL_II_NAMESPACE_CLOSE
bool restriction_is_additive(const unsigned int index) const
Definition: fe.h:3270
void get_interpolated_dof_values(const InputVector &values, Vector< number > &interpolated_values, const unsigned int fe_index=DoFHandlerType::default_fe_index) const
void vmult(Vector< number2 > &w, const Vector< number2 > &v, const bool adding=false) const
static ::ExceptionBase & ExcMessage(std::string arg1)
#define Assert(cond, exc)
Definition: exceptions.h:1411
virtual const FullMatrix< double > & get_restriction_matrix(const unsigned int child, const RefinementCase< dim > &refinement_case=RefinementCase< dim >::isotropic_refinement) const
Definition: fe.cc:305
const unsigned int dofs_per_cell
Definition: fe_base.h:282
size_type size() const