Reference documentation for deal.II version Git 3337a0c 20150331 14:50:06 +0200

#include <deal.II/numerics/fe_field_function.h>
Public Types  
typedef VectorTools::ExcPointNotAvailableHere ExcPointNotAvailableHere  DEAL_II_DEPRECATED 
Public Member Functions  
FEFieldFunction (const DH &dh, const VECTOR &data_vector, const Mapping< dim > &mapping=StaticMappingQ1< dim >::mapping)  
void  set_active_cell (const typename DH::active_cell_iterator &newcell) 
virtual void  vector_value (const Point< dim > &p, Vector< double > &values) const 
virtual double  value (const Point< dim > &p, const unsigned int component=0) const 
virtual void  value_list (const std::vector< Point< dim > > &points, std::vector< double > &values, const unsigned int component=0) const 
virtual void  vector_value_list (const std::vector< Point< dim > > &points, std::vector< Vector< double > > &values) const 
virtual void  vector_gradient (const Point< dim > &p, std::vector< Tensor< 1, dim > > &gradients) const 
virtual Tensor< 1, dim >  gradient (const Point< dim > &p, const unsigned int component=0) const 
virtual void  vector_gradient_list (const std::vector< Point< dim > > &p, std::vector< std::vector< Tensor< 1, dim > > > &gradients) const 
virtual void  gradient_list (const std::vector< Point< dim > > &p, std::vector< Tensor< 1, dim > > &gradients, const unsigned int component=0) const 
virtual double  laplacian (const Point< dim > &p, const unsigned int component=0) const 
virtual void  vector_laplacian (const Point< dim > &p, Vector< double > &values) const 
virtual void  laplacian_list (const std::vector< Point< dim > > &points, std::vector< double > &values, const unsigned int component=0) const 
virtual void  vector_laplacian_list (const std::vector< Point< dim > > &points, std::vector< Vector< double > > &values) const 
unsigned int  compute_point_locations (const std::vector< Point< dim > > &points, std::vector< typename DH::active_cell_iterator > &cells, std::vector< std::vector< Point< dim > > > &qpoints, std::vector< std::vector< unsigned int > > &maps) const 
Public Member Functions inherited from Function< dim >  
Function (const unsigned int n_components=1, const doubleinitial_time=0.0)  
virtual  ~Function ()=0 
Function &  operator= (const Function &f) 
virtual void  vector_values (const std::vector< Point< dim > > &points, std::vector< std::vector< double > > &values) const 
virtual void  vector_gradient (const Point< dim > &p, std::vector< Tensor< 1, dim, double > > &gradients) const 
virtual void  gradient_list (const std::vector< Point< dim > > &points, std::vector< Tensor< 1, dim, double > > &gradients, const unsigned int component=0) const 
virtual void  vector_gradients (const std::vector< Point< dim > > &points, std::vector< std::vector< Tensor< 1, dim, double > > > &gradients) const 
virtual void  vector_gradient_list (const std::vector< Point< dim > > &points, std::vector< std::vector< Tensor< 1, dim, double > > > &gradients) const 
std::size_t  memory_consumption () const 
Public Member Functions inherited from FunctionTime< Number >  
FunctionTime (const Number initial_time=Number(0.0))  
virtual  ~FunctionTime () 
Number  get_time () const 
virtual void  set_time (const Number new_time) 
virtual void  advance_time (const Number delta_t) 
Public Member Functions inherited from Subscriptor  
Subscriptor ()  
Subscriptor (const Subscriptor &)  
virtual  ~Subscriptor () 
Subscriptor &  operator= (const Subscriptor &) 
void  subscribe (const char *identifier=0) const 
void  unsubscribe (const char *identifier=0) const 
unsigned int  n_subscriptions () const 
void  list_subscribers () const 
DeclException3 (ExcInUse, int, char *, std::string &,<< "Object of class "<< arg2<< " is still used by "<< arg1<< " other objects."<< "\n\n"<< "(Additional information: "<< arg3<< ")\n\n"<< "See the entry in the Frequently Asked Questions of "<< "deal.II (linked to from http://www.dealii.org/) for "<< "a lot more information on what this error means and "<< "how to fix programs in which it happens.")  
DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier <"<< arg2<< "> subscribes to this object of class "<< arg1<< ". Consequently, it cannot be unsubscribed.")  
template<class Archive >  
void  serialize (Archive &ar, const unsigned int version) 
Private Types  
typedef Threads::ThreadLocalStorage < typename DH::active_cell_iterator >  cell_hint_t 
Private Member Functions  
boost::optional< Point< dim > >  get_reference_coordinates (const typename DH::active_cell_iterator &cell, const Point< dim > &point) const 
Private Attributes  
SmartPointer< const DH, FEFieldFunction< dim, DH, VECTOR > >  dh 
const VECTOR &  data_vector 
const Mapping< dim > &  mapping 
cell_hint_t  cell_hint 
const unsigned int  n_components 
Additional Inherited Members  
Public Attributes inherited from Function< dim >  
const unsigned int  n_components 
Static Public Attributes inherited from Function< dim >  
static const unsigned int  dimension 
This is an interpolation function for the given dof handler and the given solution vector. The points at which this function can be evaluated MUST be inside the domain of the dof handler, but except from this, no other requirement is given. This function is rather slow, as it needs to construct a quadrature object for the point (or set of points) where you want to evaluate your finite element function. In order to do so, it needs to find out where the points lie.
If you know in advance in which cell your points lie, you can accelerate things a bit, by calling set_active_cell before asking for values or gradients of the function. If you don't do this, and your points don't lie in the cell that is currently stored, the function GridTools::find_cell_around_point is called to find out where the point is. You can specify an optional mapping to use when looking for points in the grid. If you don't do so, this function uses a Q1 mapping.
Once the FEFieldFunction knows where the points lie, it creates a quadrature formula for those points, and calls FEValues::get_function_values or FEValues::get_function_gradients with the given quadrature points.
If you only need the quadrature points but not the values of the finite element function (you might want this for the adjoint interpolation), you can also use the function compute_point_locations
alone.
An example of how to use this function is the following:
The snippet of code above will work assuming that the second triangulation is entirely included in the first one.
FEFieldFunction is designed to be an easy way to get the results of your computations across different, possibly non matching, grids. No knowledge of the location of the points is assumed in this class, which makes it rely entirely on the GridTools::find_active_cell_around_point utility for its job. However the class can be fed an "educated guess" of where the points that will be computed actually are by using the FEFieldFunction::set_active_cell method, so if you have a smart way to tell where your points are, you will save a lot of computational time by letting this class know.
When using this class with a parallel distributed triangulation object and evaluating the solution at a particular point, not every processor will own the cell at which the solution is evaluated. Rather, it may be that the cell in which this point is found is in fact a ghost or artificial cell (see GlossArtificialCell and GlossGhostCell). If the cell is artificial, we have no access to the solution there and functions that evaluate the solution at such a point will trigger an exception of type VectorTools::ExcPointNotAvailableHere. The same kind of exception will also be produced if the cell is a ghost cell: On such cells, one could in principle evaluate the solution, but it becomes easier if we do not allow to do so because then there is exactly one processor in a parallel distributed computation that can indeed evaluate the solution. Consequently, it is clear which processor is responsible for producing output if the point evaluation is done as a postprocessing step.
To deal with this situation, you will want to use code as follows when, for example, evaluating the solution at the origin (here using a parallel TrilinosWrappers vector to hold the solution):
Definition at line 162 of file fe_field_function.h.
typedef VectorTools::ExcPointNotAvailableHere ExcPointNotAvailableHere Functions::FEFieldFunction< dim, DH, VECTOR >::DEAL_II_DEPRECATED 
Definition at line 416 of file fe_field_function.h.

private 
Typedef holding the local cell_hint.
Definition at line 424 of file fe_field_function.h.
Functions::FEFieldFunction< dim, DH, VECTOR >::FEFieldFunction  (  const DH &  dh, 
const VECTOR &  data_vector,  
const Mapping< dim > &  mapping = StaticMappingQ1< dim >::mapping 

) 
Construct a vector function. A smart pointers is stored to the dof handler, so you have to make sure that it make sense for the entire lifetime of this object. The number of components of this functions is equal to the number of components of the finite element object. If a mapping is specified, that is what is used to find out where the points lay. Otherwise the standard Q1 mapping is used.
void Functions::FEFieldFunction< dim, DH, VECTOR >::set_active_cell  (  const typename DH::active_cell_iterator &  newcell  ) 
Set the current cell. If you know in advance where your points lie, you can tell this object by calling this function. This will speed things up a little.

virtual 
Get one vector value at the given point. It is inefficient to use single points. If you need more than one at a time, use the vector_value_list() function. For efficiency reasons, it is better if all the points lie on the same cell. This is not mandatory, however it does speed things up.
Reimplemented from Function< dim >.

virtual 
Return the value of the function at the given point. Unless there is only one component (i.e. the function is scalar), you should state the component you want to have evaluated; it defaults to zero, i.e. the first component. It is inefficient to use single points. If you need more than one at a time, use the vector_value_list function. For efficiency reasons, it is better if all the points lie on the same cell. This is not mandatory, however it does speed things up.
Reimplemented from Function< dim >.

virtual 
Set values
to the point values of the specified component of the function at the points
. It is assumed that values
already has the right size, i.e. the same size as the points array. This is rather efficient if all the points lie on the same cell. If this is not the case, things may slow down a bit.
Reimplemented from Function< dim >.

virtual 
Set values
to the point values of the function at the points
. It is assumed that values
already has the right size, i.e. the same size as the points array. This is rather efficient if all the points lie on the same cell. If this is not the case, things may slow down a bit.
Reimplemented from Function< dim >.

virtual 
Return the gradient of all components of the function at the given point. It is inefficient to use single points. If you need more than one at a time, use the vector_value_list function. For efficiency reasons, it is better if all the points lie on the same cell. This is not mandatory, however it does speed things up.

virtual 
Return the gradient of the specified component of the function at the given point. It is inefficient to use single points. If you need more than one at a time, use the vector_value_list function. For efficiency reasons, it is better if all the points lie on the same cell. This is not mandatory, however it does speed things up.
Reimplemented from Function< dim >.

virtual 
Return the gradient of all components of the function at all the given points. This is rather efficient if all the points lie on the same cell. If this is not the case, things may slow down a bit.

virtual 
Return the gradient of the specified component of the function at all the given points. This is rather efficient if all the points lie on the same cell. If this is not the case, things may slow down a bit.

virtual 
Compute the Laplacian of a given component at point p
.
Reimplemented from Function< dim >.

virtual 
Compute the Laplacian of all components at point p
and store them in values
.
Reimplemented from Function< dim >.

virtual 
Compute the Laplacian of one component at a set of points.
Reimplemented from Function< dim >.

virtual 
Compute the Laplacians of all components at a set of points.
Reimplemented from Function< dim >.
unsigned int Functions::FEFieldFunction< dim, DH, VECTOR >::compute_point_locations  (  const std::vector< Point< dim > > &  points, 
std::vector< typename DH::active_cell_iterator > &  cells,  
std::vector< std::vector< Point< dim > > > &  qpoints,  
std::vector< std::vector< unsigned int > > &  maps  
)  const 
Create quadrature rules. This function groups the points into blocks that live in the same cell, and fills up three vectors: cells
, qpoints
and maps
. The first is a list of the cells that contain the points, the second is a list of quadrature points matching each cell of the first list, and the third contains the index of the given quadrature points, i.e., points
[maps[3][4]] ends up as the 5th quadrature point in the 4th cell. This is where optimization would help. This function returns the number of cells that contain the given set of points.

private 
Given a cell, return the reference coordinates of the given point within this cell if it indeed lies within the cell. Otherwise return an uninitialized boost::optional object.

private 
Pointer to the dof handler.
Definition at line 429 of file fe_field_function.h.

private 
A reference to the actual data vector.
Definition at line 434 of file fe_field_function.h.

private 
A reference to the mapping being used.
Definition at line 439 of file fe_field_function.h.

mutableprivate 
The latest cell hint.
Definition at line 444 of file fe_field_function.h.

private 
Store the number of components of this function.
Definition at line 449 of file fe_field_function.h.