Reference documentation for deal.II version Git 2e2d57a 2014-11-27 22:08:57 +0100
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Functions::ParsedFunction< dim > Class Template Reference

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

Inheritance diagram for Functions::ParsedFunction< dim >:
[legend]

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 ()
 
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
 
 DeclException0 (ExcInvalidFormula)
 
- Public Member Functions inherited from Function< dim >
 Function (const unsigned int n_components=1, const doubleinitial_time=0.0)
 
virtual ~Function ()=0
 
Functionoperator= (const Function &f)
 
virtual double value (const Point< dim, double > &p, const unsigned int component=0) const
 
virtual void vector_value (const Point< dim, double > &p, Vector< double > &values) const
 
virtual void value_list (const std::vector< Point< dim, double > > &points, std::vector< double > &values, const unsigned int component=0) const
 
virtual void vector_value_list (const std::vector< Point< dim, double > > &points, std::vector< Vector< double > > &values) const
 
virtual void vector_values (const std::vector< Point< dim, double > > &points, std::vector< std::vector< double > > &values) const
 
virtual Tensor< 1, dim, doublegradient (const Point< dim, double > &p, const unsigned int component=0) const
 
virtual void vector_gradient (const Point< dim, double > &p, std::vector< Tensor< 1, dim, double > > &gradients) const
 
virtual void gradient_list (const std::vector< Point< dim, double > > &points, std::vector< Tensor< 1, dim, double > > &gradients, const unsigned int component=0) const
 
virtual void vector_gradients (const std::vector< Point< dim, double > > &points, std::vector< std::vector< Tensor< 1, dim, double > > > &gradients) const
 
virtual void vector_gradient_list (const std::vector< Point< dim, double > > &points, std::vector< std::vector< Tensor< 1, dim, double > > > &gradients) const
 
virtual double laplacian (const Point< dim, double > &p, const unsigned int component=0) const
 
virtual void vector_laplacian (const Point< dim, double > &p, Vector< double > &values) const
 
virtual void laplacian_list (const std::vector< Point< dim, double > > &points, std::vector< double > &values, const unsigned int component=0) const
 
virtual void vector_laplacian_list (const std::vector< Point< dim, double > > &points, std::vector< Vector< 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 ()
 
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 ()
 
Subscriptoroperator= (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"<< "(Additional information: "<< arg3<< ")\n"<< "Note the entry in the Frequently Asked Questions of "<< "deal.II (linked to from http://www.dealii.org/) for "<< "more information on what this error means.")
 
 DeclException2 (ExcNoSubscriber, char *, char *,<< "No subscriber with identifier \""<< arg2<< "\" did subscribe to this object of class "<< arg1)
 
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)
 

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
// Declare a section for the function we need
prm.enter_subsection("My vector function");
// Create a ParsedFunction
ParsedFunction<dim> my_vector_function(dim);
// Parse an input file.
prm.read_input(some_input_file);
// Initialize the ParsedFunction object with the given file
prm.enter_subsection("My vector function");
my_vector_function.parse_parameters(prm);

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 80 of file parsed_function.h.

Constructor & Destructor Documentation

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.

Member Function Documentation

template<int dim>
static 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
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 convenctions 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.

template<int dim>
virtual 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.

template<int dim>
virtual 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.

template<int dim>
virtual 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>.

Member Data Documentation

template<int dim>
FunctionParser<dim> Functions::ParsedFunction< dim >::function_object
private

The object with which we do computations.

Definition at line 261 of file parsed_function.h.


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