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

Inheritance diagram for Functions::ParsedFunction< dim >:

Public Member Functions
	ParsedFunction (const unsigned int n_components=1, const double h=1e-8)

void	parse_parameters (ParameterHandler &prm)

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	set_time (const double newtime)

Public Member Functions inherited from AutoDerivativeFunction< dim >
	AutoDerivativeFunction (const double h, const unsigned int n_components=1, const double initial_time=0.0)

virtual	~AutoDerivativeFunction ()=default

void	set_formula (const DifferenceFormula formula=Euler)

void	set_h (const double h)

virtual Tensor< 1, dim >	gradient (const Point< dim > &p, const unsigned int component=0) const

virtual void	vector_gradient (const Point< dim > &p, std::vector< Tensor< 1, dim > > &gradients) const

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

virtual void	vector_gradient_list (const std::vector< Point< dim > > &points, std::vector< std::vector< Tensor< 1, dim > > > &gradients) const

Public Member Functions inherited from Function< dim >
	Function (const unsigned int n_components=1, const double initial_time=0.0)

virtual	~Function ()=0

Function &	operator= (const Function &f)

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_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

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

virtual SymmetricTensor< 2, dim, double >	hessian (const Point< dim > &p, const unsigned int component=0) const

virtual void	vector_hessian (const Point< dim > &p, std::vector< SymmetricTensor< 2, dim, double > > &values) const

virtual void	hessian_list (const std::vector< Point< dim > > &points, std::vector< SymmetricTensor< 2, dim, double > > &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, double > > > &values) const

std::size_t	memory_consumption () const

Public Member Functions inherited from FunctionTime< Number >
	FunctionTime (const Number initial_time=Number(0.0))

virtual	~FunctionTime ()=default

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 &)

	Subscriptor (Subscriptor &&) noexcept

virtual	~Subscriptor ()

Subscriptor &	operator= (const Subscriptor &)

Subscriptor &	operator= (Subscriptor &&) noexcept

void	subscribe (const char *identifier=nullptr) const

void	unsubscribe (const char *identifier=nullptr) const

unsigned int	n_subscriptions () const

void	list_subscribers () const

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

Static Public Member Functions
static void	declare_parameters (ParameterHandler &prm, const unsigned int n_components=1)

Static Public Member Functions inherited from AutoDerivativeFunction< dim >
static DifferenceFormula	get_formula_of_order (const unsigned int ord)

Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Private Attributes
FunctionParser< dim >	function_object

Additional Inherited Members
Public Types inherited from AutoDerivativeFunction< dim >
enum	DifferenceFormula { Euler, UpwindEuler, FourthOrder }

Public Attributes inherited from Function< dim >
const unsigned int	n_components

Static Public Attributes inherited from Function< dim >
static const unsigned int	dimension

Detailed Description

template<int dim>
class Functions::ParsedFunction< dim >

Friendly interface to the FunctionParser class. This class is meant as a wrapper for the FunctionParser class. It is used in the step-34 tutorial program.

It provides two methods to declare and parse a ParameterHandler object and creates the Function object declared in the parameter file. This class is derived from the AutoDerivativeFunction class, so you don't need to specify derivatives. An example of usage of this class is as follows:

// A parameter handler
ParameterHandler prm;
// Declare a section for the function we need
prm.enter_subsection("My vector function");
ParsedFunction<dim>::declare_parameters(prm, dim);
prm.leave_subsection();
// Create a ParsedFunction
ParsedFunction<dim> my_vector_function(dim);
// Parse an input file.
prm.parse_input(some_input_file);
// Initialize the ParsedFunction object with the given file
prm.enter_subsection("My vector function");
my_vector_function.parse_parameters(prm);
prm.leave_subsection();

And here is an example of how the input parameter could look like (see the documentation of the FunctionParser class for a detailed description of the syntax of the function definition):

# A test two dimensional vector function, depending on time
subsection My vector function
set Function constants  = kappa=.1, lambda=2.
set Function expression = if(y>.5, kappa*x*(1-x),0); t^2*cos(lambda*pi*x)
set Variable names      = x,y,t
end

Author: Luca Heltai, 2006

Definition at line 79 of file parsed_function.h.

Constructor & Destructor Documentation

◆ ParsedFunction()

template<int dim>

Functions::ParsedFunction< dim >::ParsedFunction	(	const unsigned int	n_components = `1`,
		const double	h = `1e-8`
	)

Construct a vector function. The vector function which is generated has n_components components (defaults to 1). The parameter h is used to initialize the AutoDerivativeFunction class from which this class is derived.

Definition at line 26 of file parsed_function.cc.

Member Function Documentation

◆ declare_parameters()

template<int dim>

void Functions::ParsedFunction< dim >::declare_parameters	(	ParameterHandler &	prm,
		const unsigned int	n_components = `1`
	)

static

Declare parameters needed by this class. The additional parameter n_components is used to generate the right code according to the number of components of the function that will parse this ParameterHandler. If the number of components which is parsed does not match the number of components of this object, an assertion is thrown and the program is aborted. The default behavior for this class is to declare the following entries:

set Function constants  =
set Function expression = 0
set Variable names      = x,y,t

Definition at line 36 of file parsed_function.cc.

◆ parse_parameters()

template<int dim>

void Functions::ParsedFunction< dim >::parse_parameters ( ParameterHandler & prm )

Parse parameters needed by this class. If the number of components which is parsed does not match the number of components of this object, an assertion is thrown and the program is aborted. In order for the class to function properly, we follow the same conventions declared in the FunctionParser class (look there for a detailed description of the syntax for function declarations).

The three variables that can be parsed from a parameter file are the following:

set Function constants  =
set Function expression =
set Variable names      =

Function constants is a collection of pairs in the form name=value, separated by commas, for example:

set Function constants = lambda=1., alpha=2., gamma=3.

These constants can be used in the declaration of the function expression, which follows the convention of the FunctionParser class. In order to specify vector functions, semicolons have to be used to separate the different components, e.g.:

set Function expression = cos(pi*x) ; cos(pi*y)

The variable names entry can be used to customize the name of the variables used in the Function. It defaults to

set Variable names = x,t

for one dimensional problems,

set Variable names = x,y,t

for two dimensional problems and

set Variable names = x,y,z,t

for three dimensional problems.

The time variable can be set according to specifications in the FunctionTime base class.

Definition at line 105 of file parsed_function.cc.

◆ vector_value()

template<int dim>

void Functions::ParsedFunction< dim >::vector_value	(	const Point< dim > &	p,
		Vector< double > &	values
	)		const

virtual

Return all components of a vector-valued function at the given point p.

Reimplemented from Function< dim >.

Definition at line 155 of file parsed_function.cc.

◆ value()

template<int dim>

double Functions::ParsedFunction< dim >::value	(	const Point< dim > &	p,
		const unsigned int	component = `0`
	)		const

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.

Reimplemented from Function< dim >.

Definition at line 164 of file parsed_function.cc.

◆ set_time()

template<int dim>

void Functions::ParsedFunction< dim >::set_time ( const double newtime )

virtual

Set the time to a specific value for time-dependent functions.

We need to overwrite this to set the time also in the accessor FunctionParser<dim>.

Definition at line 173 of file parsed_function.cc.

Member Data Documentation

◆ function_object

template<int dim>

FunctionParser<dim> Functions::ParsedFunction< dim >::function_object

private

The object with which we do computations.

Definition at line 210 of file parsed_function.h.

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

deal.II/base/parsed_function.h
source/base/parsed_function.cc

Public Member Functions

Static Public Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

template<int dim> class Functions::ParsedFunction< dim >

Constructor & Destructor Documentation

◆ ParsedFunction()

Member Function Documentation

◆ declare_parameters()

◆ parse_parameters()

◆ vector_value()

◆ value()

◆ set_time()

Member Data Documentation

◆ function_object

template<int dim>
class Functions::ParsedFunction< dim >