libMesh::DiscontinuityMeasure Class Reference

#include <discontinuity_measure.h>

Inheritance diagram for libMesh::DiscontinuityMeasure:

Public Types

typedef std::map< std::pair
< const System *, unsigned int >
, ErrorVector * > 
ErrorMap
 

Public Member Functions

 DiscontinuityMeasure ()
 
 ~DiscontinuityMeasure ()
 
void attach_essential_bc_function (std::pair< bool, Real > fptr(const System &system, const Point &p, const std::string &var_name))
 
virtual void estimate_error (const System &system, ErrorVector &error_per_cell, const NumericVector< Number > *solution_vector=NULL, bool estimate_parent_error=false)
 
virtual void estimate_errors (const EquationSystems &equation_systems, ErrorVector &error_per_cell, const std::map< const System *, SystemNorm > &error_norms, const std::map< const System *, const NumericVector< Number > * > *solution_vectors=NULL, bool estimate_parent_error=false)
 
virtual void estimate_errors (const EquationSystems &equation_systems, ErrorMap &errors_per_cell, const std::map< const System *, const NumericVector< Number > * > *solution_vectors=NULL, bool estimate_parent_error=false)
 

Public Attributes

bool scale_by_n_flux_faces
 
SystemNorm error_norm
 

Protected Member Functions

virtual void initialize (const System &system, ErrorVector &error_per_cell, bool estimate_parent_error)
 
virtual void internal_side_integration ()
 
virtual bool boundary_side_integration ()
 
void reinit_sides ()
 
float coarse_n_flux_faces_increment ()
 
void reduce_error (std::vector< float > &error_per_cell, const Parallel::Communicator &comm LIBMESH_CAN_DEFAULT_TO_COMMWORLD) const
 

Protected Attributes

const Systemmy_system
 
std::pair< bool, Real >(* _bc_function )(const System &system, const Point &p, const std::string &var_name)
 
bool integrate_boundary_sides
 
const Elemfine_elem
 
const Elemcoarse_elem
 
Real fine_error
 
Real coarse_error
 
unsigned int fine_side
 
unsigned int var
 
DenseVector< NumberUfine
 
DenseVector< NumberUcoarse
 
AutoPtr< FEBasefe_fine
 
AutoPtr< FEBasefe_coarse
 

Detailed Description

This class measures discontinuities between elements for debugging purposes. It derives from ErrorEstimator just in case someone finds it useful in a DG framework.

Author
Roy H. Stogner, 2006.

Definition at line 48 of file discontinuity_measure.h.

Member Typedef Documentation

typedef std::map<std::pair<const System*, unsigned int>, ErrorVector*> libMesh::ErrorEstimator::ErrorMap
inherited

When calculating many error vectors at once, we need a data structure to hold them all

Definition at line 109 of file error_estimator.h.

Constructor & Destructor Documentation

libMesh::DiscontinuityMeasure::DiscontinuityMeasure ( )
inline

Constructor. Responsible for initializing the _bc_function function pointer to NULL. Defaults to L2 norm; changes to system norm are ignored.

Definition at line 57 of file discontinuity_measure.h.

References libMesh::ErrorEstimator::error_norm, and libMeshEnums::L2.

57  :
59  _bc_function(NULL)
60  { error_norm = L2; }
libMesh::DiscontinuityMeasure::~DiscontinuityMeasure ( )
inline

Destructor.

Definition at line 65 of file discontinuity_measure.h.

65 {}

Member Function Documentation

void libMesh::DiscontinuityMeasure::attach_essential_bc_function ( std::pair< bool, Real >   fptrconst System &system,const Point &p,const std::string &var_name)

Register a user function to use in computing the essential BCs. The return value is std::pair<bool, Real>

Definition at line 164 of file discontinuity_measure.C.

167 {
168  _bc_function = fptr;
169 
170 // We may be turning boundary side integration on or off
171  if (fptr)
173  else
174  integrate_boundary_sides = false;
175 }
bool libMesh::DiscontinuityMeasure::boundary_side_integration ( )
protectedvirtual

The function which calculates a normal derivative jump based error term on a boundary side. Returns true if the flux bc function is in fact defined on the current side.

Reimplemented from libMesh::JumpErrorEstimator.

Definition at line 96 of file discontinuity_measure.C.

References _bc_function, libMesh::ErrorEstimator::error_norm, libMesh::JumpErrorEstimator::fe_fine, libMesh::JumpErrorEstimator::fine_elem, libMesh::JumpErrorEstimator::fine_error, libMesh::Elem::hmax(), my_system, libMesh::TensorTools::norm_sq(), libMesh::Real, libMesh::DenseVector< T >::size(), libMesh::JumpErrorEstimator::Ufine, libMesh::JumpErrorEstimator::var, libMesh::System::variable_name(), and libMesh::SystemNorm::weight().

97 {
98  const std::string &var_name = my_system->variable_name(var);
99 
100  std::vector<std::vector<Real> > phi_fine = fe_fine->get_phi();
101  std::vector<Real> JxW_face = fe_fine->get_JxW();
102  std::vector<Point> qface_point = fe_fine->get_xyz();
103 
104  // The reinitialization also recomputes the locations of
105  // the quadrature points on the side. By checking if the
106  // first quadrature point on the side is on an essential boundary
107  // for a particular variable, we will determine if the whole
108  // element is on an essential boundary (assuming quadrature points
109  // are strictly contained in the side).
110  if (this->_bc_function(*my_system, qface_point[0], var_name).first)
111  {
112  const Real h = fine_elem->hmax();
113 
114  // The number of quadrature points
115  const unsigned int n_qp = fe_fine->n_quadrature_points();
116 
117  // The error contribution from this face
118  Real error = 1.e-30;
119 
120  // loop over the integration points on the face.
121  for (unsigned int qp=0; qp<n_qp; qp++)
122  {
123  // Value of the imposed essential BC at this quadrature point.
124  const std::pair<bool,Real> essential_bc =
125  this->_bc_function(*my_system, qface_point[qp], var_name);
126 
127  // Be sure the BC function still thinks we're on the
128  // essential boundary.
129  libmesh_assert_equal_to (essential_bc.first, true);
130 
131  // The solution gradient from each element
132  Number u_fine = 0.;
133 
134  // Compute the solution gradient on element e
135  for (unsigned int i=0; i != Ufine.size(); i++)
136  u_fine += phi_fine[i][qp] * Ufine(i);
137 
138  // The difference between the desired BC and the approximate solution.
139  const Number jump = essential_bc.second - u_fine;
140 
141  // The flux jump squared. If using complex numbers,
142  // norm_sq(z) returns |z|^2, where |z| is the modulus of z.
143  const Real jump2 = TensorTools::norm_sq(jump);
144 
145  // Integrate the error on the face. The error is
146  // scaled by an additional power of h, where h is
147  // the maximum side length for the element. This
148  // arises in the definition of the indicator.
149  error += JxW_face[qp]*jump2;
150 
151  } // End quadrature point loop
152 
153  fine_error = error*h*error_norm.weight(var);
154 
155  return true;
156  } // end if side on flux boundary
157  return false;
158 }
float libMesh::JumpErrorEstimator::coarse_n_flux_faces_increment ( )
protectedinherited

A utility function to correctly increase n_flux_faces for the coarse element

Definition at line 445 of file jump_error_estimator.C.

References libMesh::JumpErrorEstimator::coarse_elem, libMesh::dim, libMesh::Elem::dim(), libMesh::JumpErrorEstimator::fine_elem, and libMesh::Elem::level().

Referenced by libMesh::JumpErrorEstimator::estimate_error().

446 {
447  // Keep track of the number of internal flux sides found on each
448  // element
449  unsigned int dim = coarse_elem->dim();
450 
451  const unsigned int divisor =
452  1 << (dim-1)*(fine_elem->level() - coarse_elem->level());
453 
454  // With a difference of n levels between fine and coarse elements,
455  // we compute a fractional flux face for the coarse element by adding:
456  // 1/2^n in 2D
457  // 1/4^n in 3D
458  // each time. This code will get hit 2^n times in 2D and 4^n
459  // times in 3D so that the final flux face count for the coarse
460  // element will be an integer value.
461 
462  return 1.0f / static_cast<float>(divisor);
463 }
void libMesh::JumpErrorEstimator::estimate_error ( const System system,
ErrorVector error_per_cell,
const NumericVector< Number > *  solution_vector = NULL,
bool  estimate_parent_error = false 
)
virtualinherited

This function uses the derived class's jump error estimate formula to estimate the error on each cell. The estimated error is output in the vector error_per_cell

Implements libMesh::ErrorEstimator.

Definition at line 54 of file jump_error_estimator.C.

References libMesh::Elem::active(), libMesh::MeshBase::active_local_elements_begin(), libMesh::MeshBase::active_local_elements_end(), libMesh::JumpErrorEstimator::boundary_side_integration(), libMesh::FEGenericBase< T >::build(), libMesh::Elem::child(), libMesh::JumpErrorEstimator::coarse_elem, libMesh::JumpErrorEstimator::coarse_error, libMesh::JumpErrorEstimator::coarse_n_flux_faces_increment(), libMesh::FEGenericBase< T >::coarsened_dof_values(), libMesh::ParallelObject::comm(), libMesh::System::current_solution(), libMesh::FEType::default_quadrature_order(), libMesh::dim, libMesh::DofMap::dof_indices(), libMesh::dof_map, libMesh::ErrorEstimator::error_norm, libMesh::ErrorVectorReal, libMesh::JumpErrorEstimator::fe_coarse, libMesh::JumpErrorEstimator::fe_fine, libMesh::JumpErrorEstimator::fine_elem, libMesh::JumpErrorEstimator::fine_error, libMesh::JumpErrorEstimator::fine_side, libMesh::System::get_dof_map(), libMesh::System::get_mesh(), libMesh::DofObject::id(), libMesh::JumpErrorEstimator::initialize(), libMesh::JumpErrorEstimator::integrate_boundary_sides, libMesh::JumpErrorEstimator::internal_side_integration(), libMesh::Elem::level(), libMesh::MeshBase::max_elem_id(), mesh, libMesh::MeshBase::mesh_dimension(), libMesh::Elem::n_children(), libMesh::Elem::n_neighbors(), libMesh::n_vars, libMesh::System::n_vars(), libMesh::Elem::neighbor(), libMesh::Elem::parent(), libMesh::ErrorEstimator::reduce_error(), libMesh::JumpErrorEstimator::reinit_sides(), libMesh::DenseVector< T >::resize(), libMesh::JumpErrorEstimator::scale_by_n_flux_faces, libMesh::System::solution, libMesh::START_LOG(), libMesh::STOP_LOG(), libMesh::NumericVector< T >::swap(), libMesh::JumpErrorEstimator::Ucoarse, libMesh::JumpErrorEstimator::Ufine, libMesh::JumpErrorEstimator::var, libMesh::DofMap::variable_type(), and libMesh::SystemNorm::weight().

58 {
59  START_LOG("estimate_error()", "JumpErrorEstimator");
60  /*
61 
62  Conventions for assigning the direction of the normal:
63 
64  - e & f are global element ids
65 
66  Case (1.) Elements are at the same level, e<f
67  Compute the flux jump on the face and
68  add it as a contribution to error_per_cell[e]
69  and error_per_cell[f]
70 
71  ----------------------
72  | | |
73  | | f |
74  | | |
75  | e |---> n |
76  | | |
77  | | |
78  ----------------------
79 
80 
81  Case (2.) The neighbor is at a higher level.
82  Compute the flux jump on e's face and
83  add it as a contribution to error_per_cell[e]
84  and error_per_cell[f]
85 
86  ----------------------
87  | | | |
88  | | e |---> n |
89  | | | |
90  |-----------| f |
91  | | | |
92  | | | |
93  | | | |
94  ----------------------
95  */
96 
97  // The current mesh
98  const MeshBase& mesh = system.get_mesh();
99 
100  // The dimensionality of the mesh
101  const unsigned int dim = mesh.mesh_dimension();
102 
103  // The number of variables in the system
104  const unsigned int n_vars = system.n_vars();
105 
106  // The DofMap for this system
107  const DofMap& dof_map = system.get_dof_map();
108 
109  // Resize the error_per_cell vector to be
110  // the number of elements, initialize it to 0.
111  error_per_cell.resize (mesh.max_elem_id());
112  std::fill (error_per_cell.begin(), error_per_cell.end(), 0.);
113 
114  // Declare a vector of floats which is as long as
115  // error_per_cell above, and fill with zeros. This vector will be
116  // used to keep track of the number of edges (faces) on each active
117  // element which are either:
118  // 1) an internal edge
119  // 2) an edge on a Neumann boundary for which a boundary condition
120  // function has been specified.
121  // The error estimator can be scaled by the number of flux edges (faces)
122  // which the element actually has to obtain a more uniform measure
123  // of the error. Use floats instead of ints since in case 2 (above)
124  // f gets 1/2 of a flux face contribution from each of his
125  // neighbors
126  std::vector<float> n_flux_faces (error_per_cell.size());
127 
128  // Prepare current_local_solution to localize a non-standard
129  // solution vector if necessary
130  if (solution_vector && solution_vector != system.solution.get())
131  {
132  NumericVector<Number>* newsol =
133  const_cast<NumericVector<Number>*>(solution_vector);
134  System &sys = const_cast<System&>(system);
135  newsol->swap(*sys.solution);
136  sys.update();
137  }
138 
139  // Loop over all the variables in the system
140  for (var=0; var<n_vars; var++)
141  {
142  // Possibly skip this variable
143  if (error_norm.weight(var) == 0.0) continue;
144 
145  // The type of finite element to use for this variable
146  const FEType& fe_type = dof_map.variable_type (var);
147 
148  // Finite element objects for the same face from
149  // different sides
150  fe_fine = FEBase::build (dim, fe_type);
151  fe_coarse = FEBase::build (dim, fe_type);
152 
153  // Build an appropriate Gaussian quadrature rule
154  QGauss qrule (dim-1, fe_type.default_quadrature_order());
155 
156  // Tell the finite element for the fine element about the quadrature
157  // rule. The finite element for the coarse element need not know about it
158  fe_fine->attach_quadrature_rule (&qrule);
159 
160  // By convention we will always do the integration
161  // on the face of element e. We'll need its Jacobian values and
162  // physical point locations, at least
163  fe_fine->get_JxW();
164  fe_fine->get_xyz();
165 
166  // Our derived classes may want to do some initialization here
167  this->initialize(system, error_per_cell, estimate_parent_error);
168 
169  // The global DOF indices for elements e & f
170  std::vector<dof_id_type> dof_indices_fine;
171  std::vector<dof_id_type> dof_indices_coarse;
172 
173 
174 
175  // Iterate over all the active elements in the mesh
176  // that live on this processor.
177  MeshBase::const_element_iterator elem_it = mesh.active_local_elements_begin();
178  const MeshBase::const_element_iterator elem_end = mesh.active_local_elements_end();
179 
180  for (; elem_it != elem_end; ++elem_it)
181  {
182  // e is necessarily an active element on the local processor
183  const Elem* e = *elem_it;
184  const dof_id_type e_id = e->id();
185 
186 #ifdef LIBMESH_ENABLE_AMR
187  // See if the parent of element e has been examined yet;
188  // if not, we may want to compute the estimator on it
189  const Elem* parent = e->parent();
190 
191  // We only can compute and only need to compute on
192  // parents with all active children
193  bool compute_on_parent = true;
194  if (!parent || !estimate_parent_error)
195  compute_on_parent = false;
196  else
197  for (unsigned int c=0; c != parent->n_children(); ++c)
198  if (!parent->child(c)->active())
199  compute_on_parent = false;
200 
201  if (compute_on_parent &&
202  !error_per_cell[parent->id()])
203  {
204  // Compute a projection onto the parent
205  DenseVector<Number> Uparent;
206  FEBase::coarsened_dof_values(*(system.solution),
207  dof_map, parent, Uparent,
208  var, false);
209 
210  // Loop over the neighbors of the parent
211  for (unsigned int n_p=0; n_p<parent->n_neighbors(); n_p++)
212  {
213  if (parent->neighbor(n_p) != NULL) // parent has a neighbor here
214  {
215  // Find the active neighbors in this direction
216  std::vector<const Elem*> active_neighbors;
217  parent->neighbor(n_p)->
218  active_family_tree_by_neighbor(active_neighbors,
219  parent);
220  // Compute the flux to each active neighbor
221  for (unsigned int a=0;
222  a != active_neighbors.size(); ++a)
223  {
224  const Elem *f = active_neighbors[a];
225  // FIXME - what about when f->level <
226  // parent->level()??
227  if (f->level() >= parent->level())
228  {
229  fine_elem = f;
230  coarse_elem = parent;
231  Ucoarse = Uparent;
232 
233  dof_map.dof_indices (fine_elem, dof_indices_fine, var);
234  const unsigned int n_dofs_fine =
235  libmesh_cast_int<unsigned int>(dof_indices_fine.size());
236  Ufine.resize(n_dofs_fine);
237 
238  for (unsigned int i=0; i<n_dofs_fine; i++)
239  Ufine(i) = system.current_solution(dof_indices_fine[i]);
240  this->reinit_sides();
242 
243  error_per_cell[fine_elem->id()] +=
244  static_cast<ErrorVectorReal>(fine_error);
245  error_per_cell[coarse_elem->id()] +=
246  static_cast<ErrorVectorReal>(coarse_error);
247 
248  // Keep track of the number of internal flux
249  // sides found on each element
250  n_flux_faces[fine_elem->id()]++;
251  n_flux_faces[coarse_elem->id()] += this->coarse_n_flux_faces_increment();
252  }
253  }
254  }
255  else if (integrate_boundary_sides)
256  {
257  fine_elem = parent;
258  Ufine = Uparent;
259 
260  // Reinitialize shape functions on the fine element side
261  fe_fine->reinit (fine_elem, fine_side);
262 
263  if (this->boundary_side_integration())
264  {
265  error_per_cell[fine_elem->id()] +=
266  static_cast<ErrorVectorReal>(fine_error);
267  n_flux_faces[fine_elem->id()]++;
268  }
269  }
270  }
271  }
272 #endif // #ifdef LIBMESH_ENABLE_AMR
273 
274  // If we do any more flux integration, e will be the fine element
275  fine_elem = e;
276 
277  // Loop over the neighbors of element e
278  for (unsigned int n_e=0; n_e<e->n_neighbors(); n_e++)
279  {
280  fine_side = n_e;
281 
282  if (e->neighbor(n_e) != NULL) // e is not on the boundary
283  {
284  const Elem* f = e->neighbor(n_e);
285  const dof_id_type f_id = f->id();
286 
287  // Compute flux jumps if we are in case 1 or case 2.
288  if ((f->active() && (f->level() == e->level()) && (e_id < f_id))
289  || (f->level() < e->level()))
290  {
291  // f is now the coarse element
292  coarse_elem = f;
293 
294  // Get the DOF indices for the two elements
295  dof_map.dof_indices (fine_elem, dof_indices_fine, var);
296  dof_map.dof_indices (coarse_elem, dof_indices_coarse, var);
297 
298  // The number of DOFS on each element
299  const unsigned int n_dofs_fine =
300  libmesh_cast_int<unsigned int>(dof_indices_fine.size());
301  const unsigned int n_dofs_coarse =
302  libmesh_cast_int<unsigned int>(dof_indices_coarse.size());
303  Ufine.resize(n_dofs_fine);
304  Ucoarse.resize(n_dofs_coarse);
305 
306  // The local solutions on each element
307  for (unsigned int i=0; i<n_dofs_fine; i++)
308  Ufine(i) = system.current_solution(dof_indices_fine[i]);
309  for (unsigned int i=0; i<n_dofs_coarse; i++)
310  Ucoarse(i) = system.current_solution(dof_indices_coarse[i]);
311 
312  this->reinit_sides();
314 
315  error_per_cell[fine_elem->id()] +=
316  static_cast<ErrorVectorReal>(fine_error);
317  error_per_cell[coarse_elem->id()] +=
318  static_cast<ErrorVectorReal>(coarse_error);
319 
320  // Keep track of the number of internal flux
321  // sides found on each element
322  n_flux_faces[fine_elem->id()]++;
323  n_flux_faces[coarse_elem->id()] += this->coarse_n_flux_faces_increment();
324  } // end if (case1 || case2)
325  } // if (e->neigbor(n_e) != NULL)
326 
327  // Otherwise, e is on the boundary. If it happens to
328  // be on a Dirichlet boundary, we need not do anything.
329  // On the other hand, if e is on a Neumann (flux) boundary
330  // with grad(u).n = g, we need to compute the additional residual
331  // (h * \int |g - grad(u_h).n|^2 dS)^(1/2).
332  // We can only do this with some knowledge of the boundary
333  // conditions, i.e. the user must have attached an appropriate
334  // BC function.
335  else
336  {
338  {
339  // Reinitialize shape functions on the fine element side
340  fe_fine->reinit (fine_elem, fine_side);
341 
342  // Get the DOF indices
343  dof_map.dof_indices (fine_elem, dof_indices_fine, var);
344 
345  // The number of DOFS on each element
346  const unsigned int n_dofs_fine =
347  libmesh_cast_int<unsigned int>(dof_indices_fine.size());
348  Ufine.resize(n_dofs_fine);
349 
350  for (unsigned int i=0; i<n_dofs_fine; i++)
351  Ufine(i) = system.current_solution(dof_indices_fine[i]);
352 
353  if (this->boundary_side_integration())
354  {
355  error_per_cell[fine_elem->id()] +=
356  static_cast<ErrorVectorReal>(fine_error);
357  n_flux_faces[fine_elem->id()]++;
358  }
359  } // end if _bc_function != NULL
360  } // end if (e->neighbor(n_e) == NULL)
361  } // end loop over neighbors
362  } // End loop over active local elements
363  } // End loop over variables
364 
365 
366 
367  // Each processor has now computed the error contribuions
368  // for its local elements. We need to sum the vector
369  // and then take the square-root of each component. Note
370  // that we only need to sum if we are running on multiple
371  // processors, and we only need to take the square-root
372  // if the value is nonzero. There will in general be many
373  // zeros for the inactive elements.
374 
375  // First sum the vector of estimated error values
376  this->reduce_error(error_per_cell, system.comm());
377 
378  // Compute the square-root of each component.
379  for (std::size_t i=0; i<error_per_cell.size(); i++)
380  if (error_per_cell[i] != 0.)
381  error_per_cell[i] = std::sqrt(error_per_cell[i]);
382 
383 
384  if (this->scale_by_n_flux_faces)
385  {
386  // Sum the vector of flux face counts
387  this->reduce_error(n_flux_faces, system.comm());
388 
389  // Sanity check: Make sure the number of flux faces is
390  // always an integer value
391 #ifdef DEBUG
392  for (unsigned int i=0; i<n_flux_faces.size(); ++i)
393  libmesh_assert_equal_to (n_flux_faces[i], static_cast<float>(static_cast<unsigned int>(n_flux_faces[i])) );
394 #endif
395 
396  // Scale the error by the number of flux faces for each element
397  for (unsigned int i=0; i<n_flux_faces.size(); ++i)
398  {
399  if (n_flux_faces[i] == 0.0) // inactive or non-local element
400  continue;
401 
402  //libMesh::out << "Element " << i << " has " << n_flux_faces[i] << " flux faces." << std::endl;
403  error_per_cell[i] /= static_cast<ErrorVectorReal>(n_flux_faces[i]);
404  }
405  }
406 
407  // If we used a non-standard solution before, now is the time to fix
408  // the current_local_solution
409  if (solution_vector && solution_vector != system.solution.get())
410  {
411  NumericVector<Number>* newsol =
412  const_cast<NumericVector<Number>*>(solution_vector);
413  System &sys = const_cast<System&>(system);
414  newsol->swap(*sys.solution);
415  sys.update();
416  }
417 
418  STOP_LOG("estimate_error()", "JumpErrorEstimator");
419 }
void libMesh::ErrorEstimator::estimate_errors ( const EquationSystems equation_systems,
ErrorVector error_per_cell,
const std::map< const System *, SystemNorm > &  error_norms,
const std::map< const System *, const NumericVector< Number > * > *  solution_vectors = NULL,
bool  estimate_parent_error = false 
)
virtualinherited

This virtual function can be redefined in derived classes, but by default computes the sum of the error_per_cell for each system in the equation_systems.

Currently this function ignores the error_norm member variable, and uses the function argument error_norms instead.

This function is named estimate_errors instead of estimate_error because otherwise C++ can get confused.

Reimplemented in libMesh::UniformRefinementEstimator.

Definition at line 48 of file error_estimator.C.

References libMesh::ErrorEstimator::error_norm, libMesh::ErrorEstimator::estimate_error(), libMesh::EquationSystems::get_system(), and libMesh::EquationSystems::n_systems().

53 {
54  SystemNorm old_error_norm = this->error_norm;
55 
56  // Sum the error values from each system
57  for (unsigned int s = 0; s != equation_systems.n_systems(); ++s)
58  {
59  ErrorVector system_error_per_cell;
60  const System &sys = equation_systems.get_system(s);
61  if (error_norms.find(&sys) == error_norms.end())
62  this->error_norm = old_error_norm;
63  else
64  this->error_norm = error_norms.find(&sys)->second;
65 
66  const NumericVector<Number>* solution_vector = NULL;
67  if (solution_vectors &&
68  solution_vectors->find(&sys) != solution_vectors->end())
69  solution_vector = solution_vectors->find(&sys)->second;
70 
71  this->estimate_error(sys, system_error_per_cell,
72  solution_vector, estimate_parent_error);
73 
74  if (s)
75  {
76  libmesh_assert_equal_to (error_per_cell.size(), system_error_per_cell.size());
77  for (unsigned int i=0; i != error_per_cell.size(); ++i)
78  error_per_cell[i] += system_error_per_cell[i];
79  }
80  else
81  error_per_cell = system_error_per_cell;
82  }
83 
84  // Restore our old state before returning
85  this->error_norm = old_error_norm;
86 }
void libMesh::ErrorEstimator::estimate_errors ( const EquationSystems equation_systems,
ErrorMap errors_per_cell,
const std::map< const System *, const NumericVector< Number > * > *  solution_vectors = NULL,
bool  estimate_parent_error = false 
)
virtualinherited

This virtual function can be redefined in derived classes, but by default it calls estimate_error repeatedly to calculate the requested error vectors.

Currently this function ignores the error_norm.weight() values because it calculates each variable's error individually, unscaled.

The user selects which errors get computed by filling a map with error vectors: If errors_per_cell[&system][v] exists, it will be filled with the error values in variable v of system

FIXME: This is a default implementation - derived classes should reimplement it for efficiency.

Reimplemented in libMesh::UniformRefinementEstimator.

Definition at line 94 of file error_estimator.C.

References libMesh::ErrorEstimator::error_norm, libMesh::ErrorEstimator::estimate_error(), libMesh::EquationSystems::get_system(), libMesh::EquationSystems::n_systems(), libMesh::n_vars, libMesh::System::n_vars(), and libMesh::SystemNorm::type().

98 {
99  SystemNorm old_error_norm = this->error_norm;
100 
101  // Find the requested error values from each system
102  for (unsigned int s = 0; s != equation_systems.n_systems(); ++s)
103  {
104  const System &sys = equation_systems.get_system(s);
105 
106  unsigned int n_vars = sys.n_vars();
107 
108  for (unsigned int v = 0; v != n_vars; ++v)
109  {
110  // Only fill in ErrorVectors the user asks for
111  if (errors_per_cell.find(std::make_pair(&sys, v)) ==
112  errors_per_cell.end())
113  continue;
114 
115  // Calculate error in only one variable
116  std::vector<Real> weights(n_vars, 0.0);
117  weights[v] = 1.0;
118  this->error_norm =
119  SystemNorm(std::vector<FEMNormType>(n_vars, old_error_norm.type(v)),
120  weights);
121 
122  const NumericVector<Number>* solution_vector = NULL;
123  if (solution_vectors &&
124  solution_vectors->find(&sys) != solution_vectors->end())
125  solution_vector = solution_vectors->find(&sys)->second;
126 
127  this->estimate_error
128  (sys, *errors_per_cell[std::make_pair(&sys, v)],
129  solution_vector, estimate_parent_error);
130  }
131  }
132 
133  // Restore our old state before returning
134  this->error_norm = old_error_norm;
135 }
void libMesh::DiscontinuityMeasure::initialize ( const System system,
ErrorVector error_per_cell,
bool  estimate_parent_error 
)
protectedvirtual

An initialization function, for requesting specific data from the FE objects

Reimplemented from libMesh::JumpErrorEstimator.

Definition at line 42 of file discontinuity_measure.C.

References libMesh::JumpErrorEstimator::fe_coarse, libMesh::JumpErrorEstimator::fe_fine, and my_system.

45 {
46  // Hang onto the system - we may need it for variable names later.
47  my_system = &system;
48 
49  // We'll need values for jump computation
50  fe_fine->get_phi();
51  fe_coarse->get_phi();
52 }
void libMesh::DiscontinuityMeasure::internal_side_integration ( )
protectedvirtual

The function which calculates a normal derivative jump based error term on an internal side

Implements libMesh::JumpErrorEstimator.

Definition at line 57 of file discontinuity_measure.C.

References libMesh::JumpErrorEstimator::coarse_elem, libMesh::JumpErrorEstimator::coarse_error, libMesh::ErrorEstimator::error_norm, libMesh::JumpErrorEstimator::fe_coarse, libMesh::JumpErrorEstimator::fe_fine, libMesh::JumpErrorEstimator::fine_elem, libMesh::JumpErrorEstimator::fine_error, libMesh::Elem::hmax(), libMesh::TensorTools::norm_sq(), libMesh::Real, libMesh::DenseVector< T >::size(), libMesh::JumpErrorEstimator::Ucoarse, libMesh::JumpErrorEstimator::Ufine, libMesh::JumpErrorEstimator::var, and libMesh::SystemNorm::weight().

58 {
59  Real error = 1.e-30;
60  unsigned int n_qp = fe_fine->n_quadrature_points();
61  unsigned int n_fine_dofs = Ufine.size();
62  unsigned int n_coarse_dofs = Ucoarse.size();
63 
64  std::vector<std::vector<Real> > phi_coarse = fe_coarse->get_phi();
65  std::vector<std::vector<Real> > phi_fine = fe_fine->get_phi();
66  std::vector<Real> JxW_face = fe_fine->get_JxW();
67 
68  for (unsigned int qp=0; qp != n_qp; ++qp)
69  {
70  // Calculate solution values on fine and coarse elements
71  // at this quadrature point
72  Number u_fine = 0., u_coarse = 0.;
73  for (unsigned int i=0; i != n_coarse_dofs; ++i)
74  u_coarse += phi_coarse[i][qp] * Ucoarse(i);
75 
76  for (unsigned int i=0; i != n_fine_dofs; ++i)
77  u_fine += phi_fine[i][qp] * Ufine(i);
78 
79  // Find the jump in the value
80  // at this quadrature point
81  const Number jump = u_fine - u_coarse;
82  const Real jump2 = TensorTools::norm_sq(jump);
83  // Accumulate the jump integral
84  error += JxW_face[qp] * jump2;
85  }
86 
87  // Add the h-weighted jump integral to each error term
88  fine_error =
89  error * fine_elem->hmax() * error_norm.weight(var);
90  coarse_error =
91  error * coarse_elem->hmax() * error_norm.weight(var);
92 }
void libMesh::ErrorEstimator::reduce_error ( std::vector< float > &  error_per_cell,
const Parallel::Communicator &comm  LIBMESH_CAN_DEFAULT_TO_COMMWORLD 
) const
protectedinherited

This method takes the local error contributions in error_per_cell from each processor and combines them to get the global error vector.

Definition at line 33 of file error_estimator.C.

References libMesh::Parallel::Communicator::sum().

Referenced by libMesh::UniformRefinementEstimator::_estimate_error(), libMesh::WeightedPatchRecoveryErrorEstimator::estimate_error(), libMesh::PatchRecoveryErrorEstimator::estimate_error(), libMesh::JumpErrorEstimator::estimate_error(), and libMesh::AdjointRefinementEstimator::estimate_error().

35 {
36  // This function must be run on all processors at once
37  // parallel_object_only();
38 
39  // Each processor has now computed the error contribuions
40  // for its local elements. We may need to sum the vector to
41  // recover the error for each element.
42 
43  comm.sum(error_per_cell);
44 }
void libMesh::JumpErrorEstimator::reinit_sides ( )
protectedinherited

A utility function to reinit the finite element data on elements sharing a side

Definition at line 424 of file jump_error_estimator.C.

References libMesh::JumpErrorEstimator::coarse_elem, libMesh::Elem::dim(), libMesh::JumpErrorEstimator::fe_coarse, libMesh::JumpErrorEstimator::fe_fine, libMesh::JumpErrorEstimator::fine_elem, libMesh::JumpErrorEstimator::fine_side, and libMesh::FEInterface::inverse_map().

Referenced by libMesh::JumpErrorEstimator::estimate_error().

425 {
426  // The master quadrature point locations on the coarse element
427  std::vector<Point> qp_coarse;
428 
429  // Reinitialize shape functions on the fine element side
430  fe_fine->reinit (fine_elem, fine_side);
431 
432  // Get the physical locations of the fine element quadrature points
433  std::vector<Point> qface_point = fe_fine->get_xyz();
434 
435  // Find their locations on the coarse element
437  coarse_elem, qface_point, qp_coarse);
438 
439  // Calculate the coarse element shape functions at those locations
440  fe_coarse->reinit (coarse_elem, &qp_coarse);
441 }

Member Data Documentation

std::pair<bool,Real>(* libMesh::DiscontinuityMeasure::_bc_function)(const System &system, const Point &p, const std::string &var_name)
protected

Pointer to function that returns BC information.

Definition at line 106 of file discontinuity_measure.h.

Referenced by boundary_side_integration().

SystemNorm libMesh::ErrorEstimator::error_norm
inherited

When estimating the error in a single system, the error_norm is used to control the scaling and norm choice for each variable. Not all estimators will support all norm choices. The default scaling is for all variables to be weighted equally. The default norm choice depends on the error estimator.

Part of this functionality was supported via component_scale and sobolev_order in older libMesh versions, and a small part was supported via component_mask in even older versions. Hopefully the encapsulation here will allow us to avoid changing this API again.

Definition at line 141 of file error_estimator.h.

Referenced by libMesh::UniformRefinementEstimator::_estimate_error(), libMesh::AdjointRefinementEstimator::AdjointRefinementEstimator(), boundary_side_integration(), libMesh::KellyErrorEstimator::boundary_side_integration(), DiscontinuityMeasure(), libMesh::JumpErrorEstimator::estimate_error(), libMesh::AdjointResidualErrorEstimator::estimate_error(), libMesh::ErrorEstimator::estimate_errors(), libMesh::ExactErrorEstimator::ExactErrorEstimator(), libMesh::ExactErrorEstimator::find_squared_element_error(), libMesh::LaplacianErrorEstimator::internal_side_integration(), internal_side_integration(), libMesh::KellyErrorEstimator::internal_side_integration(), libMesh::KellyErrorEstimator::KellyErrorEstimator(), libMesh::LaplacianErrorEstimator::LaplacianErrorEstimator(), libMesh::WeightedPatchRecoveryErrorEstimator::EstimateError::operator()(), libMesh::PatchRecoveryErrorEstimator::EstimateError::operator()(), libMesh::PatchRecoveryErrorEstimator::PatchRecoveryErrorEstimator(), and libMesh::UniformRefinementEstimator::UniformRefinementEstimator().

unsigned int libMesh::JumpErrorEstimator::fine_side
protectedinherited

Which side of the fine element is this?

Definition at line 143 of file jump_error_estimator.h.

Referenced by libMesh::JumpErrorEstimator::estimate_error(), and libMesh::JumpErrorEstimator::reinit_sides().

bool libMesh::JumpErrorEstimator::integrate_boundary_sides
protectedinherited

A boolean flag, by default false, to be set to true if integrations with boundary_side_integration() should be performed

Definition at line 128 of file jump_error_estimator.h.

Referenced by libMesh::KellyErrorEstimator::attach_flux_bc_function(), and libMesh::JumpErrorEstimator::estimate_error().

const System* libMesh::DiscontinuityMeasure::my_system
protected

A pointer to the current System

Definition at line 101 of file discontinuity_measure.h.

Referenced by boundary_side_integration(), and initialize().

bool libMesh::JumpErrorEstimator::scale_by_n_flux_faces
inherited

This boolean flag allows you to scale the error indicator result for each element by the number of "flux faces" the element actually has. This tends to weight more evenly cells which are on the boundaries and thus have fewer contributions to their flux. The value is initialized to false, simply set it to true if you want to use the feature.

Definition at line 89 of file jump_error_estimator.h.

Referenced by libMesh::JumpErrorEstimator::estimate_error().


The documentation for this class was generated from the following files:

Site Created By: libMesh Developers
Last modified: February 07 2014 16:57:59 UTC

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