Reference documentation for deal.II version Git e694e60270 2021-02-25 22:28:05 -0500
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Public Types | Public Member Functions | Static Public Member Functions | Public Attributes | Static Public Attributes | Private Attributes | List of all members
ScalarFunctionFromFunctionObject< dim, RangeNumberType > Class Template Reference

#include <deal.II/base/function.h>

Inheritance diagram for ScalarFunctionFromFunctionObject< dim, RangeNumberType >:
[legend]

Public Types

using time_type = typename FunctionTime< typename numbers::NumberTraits< RangeNumberType >::real_type >::time_type
 

Public Member Functions

 ScalarFunctionFromFunctionObject (const std::function< RangeNumberType(const Point< dim > &)> &function_object)
 
virtual RangeNumberType value (const Point< dim > &p, const unsigned int component=0) const override
 
virtual void vector_value (const Point< dim > &p, Vector< RangeNumberType > &values) const
 
virtual void value_list (const std::vector< Point< dim >> &points, std::vector< RangeNumberType > &values, const unsigned int component=0) const
 
virtual void vector_value_list (const std::vector< Point< dim >> &points, std::vector< Vector< RangeNumberType >> &values) const
 
virtual void vector_values (const std::vector< Point< dim >> &points, std::vector< std::vector< RangeNumberType >> &values) const
 
virtual Tensor< 1, dim, RangeNumberType > gradient (const Point< dim > &p, const unsigned int component=0) const
 
virtual void vector_gradient (const Point< dim > &p, std::vector< Tensor< 1, dim, RangeNumberType >> &gradients) const
 
virtual void gradient_list (const std::vector< Point< dim >> &points, std::vector< Tensor< 1, dim, RangeNumberType >> &gradients, const unsigned int component=0) const
 
virtual void vector_gradients (const std::vector< Point< dim >> &points, std::vector< std::vector< Tensor< 1, dim, RangeNumberType >>> &gradients) const
 
virtual void vector_gradient_list (const std::vector< Point< dim >> &points, std::vector< std::vector< Tensor< 1, dim, RangeNumberType >>> &gradients) const
 
virtual RangeNumberType laplacian (const Point< dim > &p, const unsigned int component=0) const
 
virtual void vector_laplacian (const Point< dim > &p, Vector< RangeNumberType > &values) const
 
virtual void laplacian_list (const std::vector< Point< dim >> &points, std::vector< RangeNumberType > &values, const unsigned int component=0) const
 
virtual void vector_laplacian_list (const std::vector< Point< dim >> &points, std::vector< Vector< RangeNumberType >> &values) const
 
virtual SymmetricTensor< 2, dim, RangeNumberType > hessian (const Point< dim > &p, const unsigned int component=0) const
 
virtual void vector_hessian (const Point< dim > &p, std::vector< SymmetricTensor< 2, dim, RangeNumberType >> &values) const
 
virtual void hessian_list (const std::vector< Point< dim >> &points, std::vector< SymmetricTensor< 2, dim, RangeNumberType >> &values, const unsigned int component=0) const
 
virtual void vector_hessian_list (const std::vector< Point< dim >> &points, std::vector< std::vector< SymmetricTensor< 2, dim, RangeNumberType >>> &values) const
 
virtual std::size_t memory_consumption () const
 
numbers::NumberTraits< RangeNumberType >::real_type get_time () const
 
virtual void set_time (const numbers::NumberTraits< RangeNumberType >::real_type new_time)
 
virtual void advance_time (const numbers::NumberTraits< RangeNumberType >::real_type delta_t)
 
template<class Archive >
void serialize (Archive &ar, const unsigned int version)
 
Subscriptor functionality

Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.

void subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
 
void unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
 
unsigned int n_subscriptions () const
 
template<typename StreamType >
void list_subscribers (StreamType &stream) const
 
void list_subscribers () const
 

Static Public Member Functions

static ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
 
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)
 

Public Attributes

const unsigned int n_components
 

Static Public Attributes

static const unsigned int dimension = dim
 

Private Attributes

const std::function< RangeNumberType(const Point< dim > &)> function_object
 

Detailed Description

template<int dim, typename RangeNumberType = double>
class ScalarFunctionFromFunctionObject< dim, RangeNumberType >

This class provides a way to convert a scalar function of the kind

RangeNumberType foo (const Point<dim> &);

into an object of type Function<dim>. Since the argument returns a scalar, the result is clearly a Function object for which function.n_components == 1. The class works by storing a pointer to the given function and every time function.value(p,component) is called, calls foo(p) and returns the corresponding value. It also makes sure that component is in fact zero, as needs be for scalar functions.

The class provides an easy way to turn a simple global function into something that has the required Function<dim> interface for operations like VectorTools::interpolate_boundary_values() etc., and thereby allows for simpler experimenting without having to write all the boiler plate code of declaring a class that is derived from Function and implementing the Function::value() function. An example of this is given in the results section of step-53.

The class gains additional expressive power because the argument it takes does not have to be a pointer to an actual function. Rather, it is a function object, i.e., it can also be the result of a lambda function or some other object that can be called with a single argument. For example, if you need a Function object that returns the norm of a point, you could write it like so:

template <int dim, typename RangeNumberType>
class Norm : public Function<dim, RangeNumberType>
{
public:
virtual RangeNumberType
value(const Point<dim> & p,
const unsigned int component) const
{
Assert (component == 0, ExcMessage ("This object is scalar!"));
return p.norm();
}
};
Norm<2> my_norm_object;

and then pass the my_norm_object around, or you could write it like so:

Similarly, to generate an object that computes the distance to a point q, we could do this:

template <int dim, typename RangeNumberType>
class DistanceTo : public Function<dim, RangeNumberType>
{
public:
DistanceTo (const Point<dim> &q) : q(q) {}
virtual RangeNumberType
value (const Point<dim> & p,
const unsigned int component) const
{
Assert(component == 0, ExcMessage("This object is scalar!"));
return q.distance(p);
}
private:
const Point<dim> q;
};
Point<2> q (2, 3);
DistanceTo<2> my_distance_object;

or we could write it like so:

[&q](const Point<dim> &p){return q.distance(p);});

The savings in work to write this are apparent.

Definition at line 702 of file function.h.

Member Typedef Documentation

◆ time_type

template<int dim, typename RangeNumberType = double>
using Function< dim, RangeNumberType >::time_type = typename FunctionTime< typename numbers::NumberTraits<RangeNumberType>::real_type>::time_type
inherited

The scalar-valued real type used for representing time.

Definition at line 170 of file function.h.

Constructor & Destructor Documentation

◆ ScalarFunctionFromFunctionObject()

template<int dim, typename RangeNumberType = double>
ScalarFunctionFromFunctionObject< dim, RangeNumberType >::ScalarFunctionFromFunctionObject ( const std::function< RangeNumberType(const Point< dim > &)> &  function_object)
explicit

Given a function object that takes a Point and returns a RangeNumberType value, convert this into an object that matches the Function<dim, RangeNumberType> interface.

Member Function Documentation

◆ value()

template<int dim, typename RangeNumberType = double>
virtual RangeNumberType ScalarFunctionFromFunctionObject< dim, RangeNumberType >::value ( const Point< dim > &  p,
const unsigned int  component = 0 
) const
overridevirtual

Return the value of the function at the given point. Returns the value the function given to the constructor produces for this point.

Reimplemented from Function< dim, RangeNumberType >.

◆ vector_value()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_value ( const Point< dim > &  p,
Vector< RangeNumberType > &  values 
) const
virtualinherited

◆ value_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::value_list ( const std::vector< Point< dim >> &  points,
std::vector< RangeNumberType > &  values,
const unsigned int  component = 0 
) const
virtualinherited

◆ vector_value_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_value_list ( const std::vector< Point< dim >> &  points,
std::vector< Vector< RangeNumberType >> &  values 
) const
virtualinherited

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, and that all elements be vectors with the same number of components as this function has.

By default, this function repeatedly calls vector_value() for each point separately, to fill the output array.

Reimplemented in Functions::CutOffFunctionCinfty< dim >, Functions::CutOffFunctionC1< dim >, Functions::CutOffFunctionW1< dim >, Functions::CutOffFunctionLinfty< dim >, VectorFunctionFromTensorFunction< dim, RangeNumberType >, ComponentSelectFunction< dim, RangeNumberType >, Functions::SlitSingularityFunction< dim >, Functions::ConstantFunction< dim, RangeNumberType >, Functions::CosineGradFunction< dim >, Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >, Functions::CosineFunction< dim >, Functions::FlowFunction< dim >, Functions::FlowFunction< 2 >, and Functions::Q1WedgeFunction< dim >.

◆ vector_values()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_values ( const std::vector< Point< dim >> &  points,
std::vector< std::vector< RangeNumberType >> &  values 
) const
virtualinherited

For each component of the function, fill a vector of values, one for each point.

The default implementation of this function in Function calls value_list() for each component. In order to improve performance, this can be reimplemented in derived classes to speed up performance.

Reimplemented in Functions::StokesCosine< dim >, Functions::PoisseuilleFlow< dim >, Functions::FlowFunction< dim >, and Functions::FlowFunction< 2 >.

◆ gradient()

template<int dim, typename RangeNumberType = double>
virtual Tensor<1, dim, RangeNumberType> Function< dim, RangeNumberType >::gradient ( const Point< dim > &  p,
const unsigned int  component = 0 
) const
virtualinherited

◆ vector_gradient()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_gradient ( const Point< dim > &  p,
std::vector< Tensor< 1, dim, RangeNumberType >> &  gradients 
) const
virtualinherited

Return the gradient of all components of the function at the given point.

Reimplemented in Functions::ConstantFunction< dim, RangeNumberType >, and Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >.

◆ gradient_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::gradient_list ( const std::vector< Point< dim >> &  points,
std::vector< Tensor< 1, dim, RangeNumberType >> &  gradients,
const unsigned int  component = 0 
) const
virtualinherited

Set gradients to the gradients of the specified component of the function at the points. It is assumed that gradients already has the right size, i.e. the same size as the points array.

Reimplemented in Functions::ConstantFunction< dim, RangeNumberType >, and Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >.

◆ vector_gradients()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_gradients ( const std::vector< Point< dim >> &  points,
std::vector< std::vector< Tensor< 1, dim, RangeNumberType >>> &  gradients 
) const
virtualinherited

For each component of the function, fill a vector of gradient values, one for each point.

The default implementation of this function in Function calls value_list() for each component. In order to improve performance, this can be reimplemented in derived classes to speed up performance.

◆ vector_gradient_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_gradient_list ( const std::vector< Point< dim >> &  points,
std::vector< std::vector< Tensor< 1, dim, RangeNumberType >>> &  gradients 
) const
virtualinherited

Set gradients to the gradients of the function at the points, for all components. It is assumed that gradients already has the right size, i.e. the same size as the points array.

The outer loop over gradients is over the points in the list, the inner loop over the different components of the function.

Reimplemented in Functions::ConstantFunction< dim, RangeNumberType >, and Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >.

◆ laplacian()

template<int dim, typename RangeNumberType = double>
virtual RangeNumberType Function< dim, RangeNumberType >::laplacian ( const Point< dim > &  p,
const unsigned int  component = 0 
) const
virtualinherited

◆ vector_laplacian()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_laplacian ( const Point< dim > &  p,
Vector< RangeNumberType > &  values 
) const
virtualinherited

Compute the Laplacian of all components at point p and store them in values.

Reimplemented in Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >.

◆ laplacian_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::laplacian_list ( const std::vector< Point< dim >> &  points,
std::vector< RangeNumberType > &  values,
const unsigned int  component = 0 
) const
virtualinherited

◆ vector_laplacian_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_laplacian_list ( const std::vector< Point< dim >> &  points,
std::vector< Vector< RangeNumberType >> &  values 
) const
virtualinherited

Compute the Laplacians of all components at a set of points.

Reimplemented in Functions::FEFieldFunction< dim, DoFHandlerType, VectorType >, Functions::FlowFunction< dim >, and Functions::FlowFunction< 2 >.

◆ hessian()

template<int dim, typename RangeNumberType = double>
virtual SymmetricTensor<2, dim, RangeNumberType> Function< dim, RangeNumberType >::hessian ( const Point< dim > &  p,
const unsigned int  component = 0 
) const
virtualinherited

Compute the Hessian of a given component at point p, that is the gradient of the gradient of the function.

Reimplemented in Functions::ConstantFunction< dim, RangeNumberType >, Functions::SymbolicFunction< dim, RangeNumberType >, Functions::CosineFunction< dim >, Functions::CSpline< dim >, and Functions::Spherical< dim >.

◆ vector_hessian()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_hessian ( const Point< dim > &  p,
std::vector< SymmetricTensor< 2, dim, RangeNumberType >> &  values 
) const
virtualinherited

Compute the Hessian of all components at point p and store them in values.

◆ hessian_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::hessian_list ( const std::vector< Point< dim >> &  points,
std::vector< SymmetricTensor< 2, dim, RangeNumberType >> &  values,
const unsigned int  component = 0 
) const
virtualinherited

Compute the Hessian of one component at a set of points.

◆ vector_hessian_list()

template<int dim, typename RangeNumberType = double>
virtual void Function< dim, RangeNumberType >::vector_hessian_list ( const std::vector< Point< dim >> &  points,
std::vector< std::vector< SymmetricTensor< 2, dim, RangeNumberType >>> &  values 
) const
virtualinherited

Compute the Hessians of all components at a set of points.

◆ memory_consumption()

template<int dim, typename RangeNumberType = double>
virtual std::size_t Function< dim, RangeNumberType >::memory_consumption ( ) const
virtualinherited

◆ get_time()

numbers::NumberTraits< RangeNumberType >::real_type FunctionTime< numbers::NumberTraits< RangeNumberType >::real_type >::get_time ( ) const
inherited

Return the value of the time variable.

◆ set_time()

virtual void FunctionTime< numbers::NumberTraits< RangeNumberType >::real_type >::set_time ( const numbers::NumberTraits< RangeNumberType >::real_type  new_time)
virtualinherited

Set the time to new_time, overwriting the old value.

◆ advance_time()

virtual void FunctionTime< numbers::NumberTraits< RangeNumberType >::real_type >::advance_time ( const numbers::NumberTraits< RangeNumberType >::real_type  delta_t)
virtualinherited

Advance the time by the given time step delta_t.

◆ subscribe()

void Subscriptor::subscribe ( std::atomic< bool > *const  validity,
const std::string &  identifier = "" 
) const
inherited

Subscribes a user of the object by storing the pointer validity. The subscriber may be identified by text supplied as identifier.

Definition at line 136 of file subscriptor.cc.

◆ unsubscribe()

void Subscriptor::unsubscribe ( std::atomic< bool > *const  validity,
const std::string &  identifier = "" 
) const
inherited

Unsubscribes a user from the object.

Note
The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 156 of file subscriptor.cc.

◆ n_subscriptions()

unsigned int Subscriptor::n_subscriptions ( ) const
inlineinherited

Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.

Definition at line 301 of file subscriptor.h.

◆ list_subscribers() [1/2]

template<typename StreamType >
void Subscriptor::list_subscribers ( StreamType &  stream) const
inlineinherited

List the subscribers to the input stream.

Definition at line 318 of file subscriptor.h.

◆ list_subscribers() [2/2]

void Subscriptor::list_subscribers ( ) const
inherited

List the subscribers to deallog.

Definition at line 204 of file subscriptor.cc.

◆ serialize()

template<class Archive >
void Subscriptor::serialize ( Archive &  ar,
const unsigned int  version 
)
inlineinherited

Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.

This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.

Definition at line 310 of file subscriptor.h.

Member Data Documentation

◆ function_object

template<int dim, typename RangeNumberType = double>
const std::function<RangeNumberType(const Point<dim> &)> ScalarFunctionFromFunctionObject< dim, RangeNumberType >::function_object
private

The function object which we call when this class's value() or value_list() functions are called.

Definition at line 725 of file function.h.

◆ dimension

template<int dim, typename RangeNumberType = double>
const unsigned int Function< dim, RangeNumberType >::dimension = dim
staticinherited

Export the value of the template parameter as a static member constant. Sometimes useful for some expression template programming.

Definition at line 159 of file function.h.

◆ n_components

template<int dim, typename RangeNumberType = double>
const unsigned int Function< dim, RangeNumberType >::n_components
inherited

Number of vector components.

Definition at line 164 of file function.h.


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