Reference documentation for deal.II version 9.4.0
TensorFunctionParser< rank, dim, Number > Class Template Reference

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

Inheritance diagram for TensorFunctionParser< rank, dim, Number >:
[legend]

## Public Types

using ConstMap = std::map< std::string, double >

using value_type = Tensor< rank, dim, double >

using gradient_type = Tensor< rank+1, dim, double >

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

## Public Member Functions

TensorFunctionParser (const double initial_time=0.0)

TensorFunctionParser (const std::string &expression, const std::string &constants="", const std::string &variable_names=default_variable_names()+",t")

TensorFunctionParser (const TensorFunctionParser &)=delete

TensorFunctionParser (TensorFunctionParser &&)=delete

TensorFunctionParseroperator= (const TensorFunctionParser &)=delete

TensorFunctionParseroperator= (TensorFunctionParser &&)=delete

virtual void initialize (const std::string &vars, const std::vector< std::string > &expressions, const ConstMap &constants, const bool time_dependent=false) override

void initialize (const std::string &vars, const std::string &expression, const ConstMap &constants, const bool time_dependent=false)

virtual Tensor< rank, dim, Number > value (const Point< dim > &p) const override

virtual void value_list (const std::vector< Point< dim > > &p, std::vector< Tensor< rank, dim, Number > > &values) const override

const std::vector< std::string > & get_expressions () const

virtual void value_list (const std::vector< Point< dim > > &points, std::vector< value_type > &values) const

numbers::NumberTraits< double >::real_type get_time () const

virtual void set_time (const numbers::NumberTraits< double >::real_type new_time)

virtual void advance_time (const numbers::NumberTraits< double >::real_type delta_t)

## Static Public Member Functions

static std::string default_variable_names ()

static ::ExceptionBaseExcParseError (int arg1, std::string arg2)

static ::ExceptionBaseExcInvalidExpressionSize (int arg1, int arg2)

## Protected Member Functions

void init_muparser () const

double do_value (const Point< dim > &p, const double time, unsigned int component) const

void do_all_values (const Point< dim > &p, const double time, ArrayView< double > &values) const

## Protected Attributes

std::vector< std::string > expressions

## Private Attributes

unsigned int n_components

numbers::NumberTraits< double >::real_type time

std::map< std::string, double > constants

std::vector< std::string > var_names

bool initialized

unsigned int n_vars

## Subscriptor functionality

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

std::atomic< unsigned intcounter

std::map< std::string, unsigned intcounter_map

std::vector< std::atomic< bool > * > validity_pointers

const std::type_info * object_info

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

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

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

static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)

using map_value_type = decltype(counter_map)::value_type

using map_iterator = decltype(counter_map)::iterator

static std::mutex mutex

void check_no_subscribers () const noexcept

## Detailed Description

template<int rank, int dim, typename Number = double>
class TensorFunctionParser< rank, dim, Number >

This class implements a tensor function object that gets its value by parsing a string describing this function. It is a wrapper class for the muparser library (see http://muparser.beltoforion.de/). This class is essentially an extension of the FunctionParser class to read in a TensorFunction. The class reads in an expression of length dimrank (separated by a semicolon) where the components of the tensor function are filled according to the C++ convention (fastest index is the most right one).

Note
In contrast to the FunctionParser class the TensorFunctionParser class does not support automatic differentiation.

A minimal example for the usage of the class would be:

// set up time dependent tensor function:
const std::string variables = "x,y,t";
const std::string expression =
"exp(-t)*cos(x+y);-sin(pi*x*y-t);sin(pi*x*y-t);exp(t)*cos(x+y)";
std::map<std::string,double> constants;
// TensorFunctionParser with 2+1 variables (space + time) in 2D of rank 2.
// It is necessary to tell the parser that there is an additional variable
// to be taken into account (t).
tfp.initialize(variables,
expression,
true); // flag for time dependence
// Point at which we want to evaluate the function
Point<2> point(0.0, 1.0);
// evaluate the expression at 'point':
double result = tfp.value(point);
deallog << "Function '" << expression << "'"
<< " @ " << point
<< " is: "
<< std::endl
<< result[0][0] << ' ' << result[0][1] << std::endl
<< result[1][0] << ' ' << result[1][1]
<< std::endl;
virtual Tensor< rank, dim, Number > value(const Point< dim > &p) const override
virtual void initialize(const std::string &vars, const std::vector< std::string > &expressions, const ConstMap &constants, const bool time_dependent=false) override
LogStream deallog
Definition: logstream.cc:37
Point< spacedim > point(const gp_Pnt &p, const double tolerance=1e-10)
Definition: utilities.cc:190
static constexpr double PI
Definition: numbers.h:233

This class overloads the virtual method value() and value_list() of the TensorFunction base class with the byte compiled versions of the expressions given to the initialize() methods. Note that the class will not work unless you first call the initialize() method that accepts the text description of the function as an argument (among other things).

The syntax to describe a function follows usual programming practice, and is explained in detail at the homepage of the underlying muparser library at http://muparser.beltoforion.de/ .

Vector-valued functions can either be declared using strings where the function components are separated by semicolons, or using a vector of strings each defining one vector component.

Definition at line 106 of file tensor_function_parser.h.

## ◆ ConstMap

template<int rank, int dim, typename Number = double>
 using TensorFunctionParser< rank, dim, Number >::ConstMap = std::map

Type for the constant map. Used by the initialize() method.

Definition at line 161 of file tensor_function_parser.h.

## ◆ value_type

 using TensorFunction< rank, dim, double >::value_type = Tensor
inherited

Alias for the return types of the value function.

Definition at line 64 of file tensor_function.h.

 using TensorFunction< rank, dim, double >::gradient_type = Tensor
inherited

Alias for the return types of the gradient functions.

Definition at line 69 of file tensor_function.h.

## ◆ time_type

 using TensorFunction< rank, dim, double >::time_type = typename FunctionTime< typename numbers::NumberTraits::real_type>::time_type
inherited

The scalar-valued real type used for representing time.

Definition at line 74 of file tensor_function.h.

## ◆ TensorFunctionParser() [1/4]

template<int rank, int dim, typename Number >
 TensorFunctionParser< rank, dim, Number >::TensorFunctionParser ( const double initial_time = 0.0 )

Standard constructor. Only set initial time. This object needs to be initialized with the initialize() method before you can use it. If an attempt to use this function is made before the initialize() method has been called, then an exception is thrown.

Definition at line 40 of file tensor_function_parser.cc.

## ◆ TensorFunctionParser() [2/4]

template<int rank, int dim, typename Number >
 TensorFunctionParser< rank, dim, Number >::TensorFunctionParser ( const std::string & expression, const std::string & constants = "", const std::string & variable_names = default_variable_names() + ",t" )

Constructor for parsed functions. This object needs to be initialized with the initialize() method before you can use it. If an attempt to use this function is made before the initialize() method has been called, then an exception is thrown. Takes a semicolon separated list of expressions (one for each component of the tensor function), an optional comma-separated list of constants.

Definition at line 48 of file tensor_function_parser.cc.

## ◆ TensorFunctionParser() [3/4]

template<int rank, int dim, typename Number = double>
 TensorFunctionParser< rank, dim, Number >::TensorFunctionParser ( const TensorFunctionParser< rank, dim, Number > & )
delete

Copy constructor. Objects of this type can not be copied, and consequently this constructor is deleted.

## ◆ TensorFunctionParser() [4/4]

template<int rank, int dim, typename Number = double>
 TensorFunctionParser< rank, dim, Number >::TensorFunctionParser ( TensorFunctionParser< rank, dim, Number > && )
delete

Move constructor. Objects of this type can not be moved, and consequently this constructor is deleted.

## ◆ operator=() [1/2]

template<int rank, int dim, typename Number = double>
 TensorFunctionParser & TensorFunctionParser< rank, dim, Number >::operator= ( const TensorFunctionParser< rank, dim, Number > & )
delete

Copy operator. Objects of this type can not be copied, and consequently this operator is deleted.

## ◆ operator=() [2/2]

template<int rank, int dim, typename Number = double>
 TensorFunctionParser & TensorFunctionParser< rank, dim, Number >::operator= ( TensorFunctionParser< rank, dim, Number > && )
delete

Move operator. Objects of this type can not be moved, and consequently this operator is deleted.

## ◆ initialize() [1/2]

template<int rank, int dim, typename Number >
 void TensorFunctionParser< rank, dim, Number >::initialize ( const std::string & vars, const std::vector< std::string > & expressions, const ConstMap & constants, const bool time_dependent = false )
overridevirtual

Initialize the tensor function. This method accepts the following parameters:

Parameters
 [in] vars A string with the variables that will be used by the expressions to be evaluated. Note that the variables can have any name (of course different from the function names defined above!), but the order IS important. The first variable will correspond to the first component of the point in which the function is evaluated, the second variable to the second component and so forth. If this function is also time dependent, then it is necessary to specify it by setting the time_dependent parameter to true. An exception is thrown if the number of variables specified here is different from dim (if this function is not time-dependent) or from dim+1 (if it is time-dependent). [in] expressions A vector of strings containing the expressions that will be byte compiled by the internal parser (TensorFunctionParser). Note that the size of this vector must match exactly the number of components of the TensorFunctionParser, as declared in the constructor. If this is not the case, an exception is thrown. [in] constants A map of constants used to pass any necessary constant that we want to specify in our expressions (in the example above the number pi). An expression is valid if and only if it contains only defined variables and defined constants (other than the functions specified above). If a constant is given whose name is not valid (eg: constants["sin"] = 1.5;) an exception is thrown. [in] time_dependent If this is a time dependent function, then the last variable declared in vars is assumed to be the time variable, and this->get_time() is used to initialize it when evaluating the function. Naturally the number of variables parsed by the initialize() method in this case is dim+1. The value of this parameter defaults to false, i.e. do not consider time.

Reimplemented from internal::FunctionParser::ParserImplementation< dim, double >.

Definition at line 74 of file tensor_function_parser.cc.

## ◆ initialize() [2/2]

template<int rank, int dim, typename Number >
 void TensorFunctionParser< rank, dim, Number >::initialize ( const std::string & vars, const std::string & expression, const ConstMap & constants, const bool time_dependent = false )

Initialize the function. Same as above, but accepts a string rather than a vector of strings. If this is a vector valued function, its components are expected to be separated by a semicolon. An exception is thrown if this method is called and the number of components successfully parsed does not match the number of components of the base function.

Definition at line 90 of file tensor_function_parser.cc.

## ◆ default_variable_names()

template<int rank, int dim, typename Number >
 std::string TensorFunctionParser< rank, dim, Number >::default_variable_names
static

A function that returns default names for variables, to be used in the first argument of the initialize() functions: it returns "x" in 1d, "x,y" in 2d, and "x,y,z" in 3d.

Definition at line 274 of file tensor_function_parser.h.

## ◆ value()

template<int rank, int dim, typename Number >
 Tensor< rank, dim, Number > TensorFunctionParser< rank, dim, Number >::value ( const Point< dim > & p ) const
overridevirtual

Return the value of the tensor function at the given point.

Reimplemented from TensorFunction< rank, dim, double >.

Definition at line 106 of file tensor_function_parser.cc.

## ◆ value_list() [1/2]

template<int rank, int dim, typename Number >
 void TensorFunctionParser< rank, dim, Number >::value_list ( const std::vector< Point< dim > > & p, std::vector< Tensor< rank, dim, Number > > & values ) const
overridevirtual

Return the value of the tensor function at the given point.

Definition at line 121 of file tensor_function_parser.cc.

## ◆ get_expressions()

template<int rank, int dim, typename Number >
 const std::vector< std::string > & TensorFunctionParser< rank, dim, Number >::get_expressions

Return an array of function expressions (one per component), used to initialize this function.

Definition at line 32 of file tensor_function_parser.cc.

## ◆ value_list() [2/2]

 virtual void TensorFunction< rank, dim, double >::value_list ( const std::vector< Point< dim > > & points, std::vector< value_type > & 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.

 virtual gradient_type TensorFunction< rank, dim, double >::gradient ( const Point< dim > & p ) const
virtualinherited

Return the gradient of the function at the given point.

Reimplemented in ConstantTensorFunction< rank, dim, Number >, and ConstantTensorFunction< rank, dim, double >.

 virtual void TensorFunction< rank, dim, double >::gradient_list ( const std::vector< Point< dim > > & points, std::vector< gradient_type > & gradients ) const
virtualinherited

Set gradients to the gradients 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.

## ◆ get_time()

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

Return the value of the time variable.

## ◆ set_time()

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

Set the time to new_time, overwriting the old value.

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

Advance the time by the given time step delta_t.

## ◆ init_muparser()

 void internal::FunctionParser::ParserImplementation< dim, double >::init_muparser
inherited

Set up the internal muParser objects to parse and evaluate mathematical expressions.

Definition at line 181 of file mu_parser_internal.cc.

## ◆ do_value()

 double internal::FunctionParser::ParserImplementation< dim, double >::do_value ( const Point< dim > & p, const double time, unsigned int component ) const
inherited

Compute the value of a single component.

Definition at line 187 of file mu_parser_internal.cc.

## ◆ do_all_values()

 void internal::FunctionParser::ParserImplementation< dim, double >::do_all_values ( const Point< dim > & p, const double time, ArrayView< double > & values ) const
inherited

Compute the values of all components.

Definition at line 195 of file mu_parser_internal.cc.

## ◆ time

 numbers::NumberTraits< double >::real_type FunctionTime< numbers::NumberTraits< double >::real_type >::time
privateinherited

Store the present time.

Definition at line 113 of file function_time.h.

## ◆ expressions

 std::vector internal::FunctionParser::ParserImplementation< dim, double >::expressions
inherited

An array of function expressions (one per component), required to initialize tfp in each thread.

Definition at line 203 of file mu_parser_internal.h.

## ◆ parser_data

mutableprivateinherited

The muParser objects (hidden with the PIMPL idiom) for each thread (and one for each component).

Definition at line 211 of file mu_parser_internal.h.

## ◆ constants

 std::map internal::FunctionParser::ParserImplementation< dim, double >::constants
privateinherited

An array to keep track of all the constants, required to initialize fp in each thread.

Definition at line 217 of file mu_parser_internal.h.

## ◆ var_names

 std::vector internal::FunctionParser::ParserImplementation< dim, double >::var_names
privateinherited

An array for the variable names, required to initialize fp in each thread.

Definition at line 223 of file mu_parser_internal.h.

## ◆ initialized

 bool internal::FunctionParser::ParserImplementation< dim, double >::initialized
privateinherited

State of usability. This variable is checked every time the function is called for evaluation. It's set to true in the initialize() methods.

Definition at line 229 of file mu_parser_internal.h.

## ◆ n_vars

 unsigned int internal::FunctionParser::ParserImplementation< dim, double >::n_vars
privateinherited

Number of variables. If this is also a function of time, then the number of variables is dim+1, otherwise it is dim. In the case that this is a time dependent function, the time is supposed to be the last variable. If n_vars is not identical to the number of the variables parsed by the initialize() method, then an exception is thrown.

Definition at line 238 of file mu_parser_internal.h.

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