The Function class is a polynomial Term that represents a generic function \( f : x \mapsto f(x) \). More...

#include <Function.h>

Inheritance diagram for fl::Function:

Collaboration diagram for fl::Function:

Classes
struct	Element
	The Element class represents a single element in a formula, be that either a function or an operator. More...

struct	Node
	The Node class structures a binary tree by storing pointers to a left Node and a right Node, and storing its content as a Function::Element, the name of an InputVariable or OutputVariable, or a constant value. More...

Public Types
typedef scalar(*	Unary) (scalar)

typedef scalar(*	Binary) (scalar, scalar)

Public Member Functions
	Function (const std::string &name="", const std::string &formula="", const Engine *engine=fl::null)

	Function (const Function &other)

Function &	operator= (const Function &other)

virtual	~Function () FL_IOVERRIDE

virtual Complexity	complexity () const FL_IOVERRIDE
	Computes the estimated complexity of evaluating the membership function. More...

virtual scalar	membership (scalar x) const FL_IOVERRIDE
	Computes the membership function value of \(x\) at the root node. More...

virtual scalar	evaluate (const std::map< std::string, scalar > *variables=fl::null) const
	Computes the function value of this term using the given map of variable substitutions. More...

virtual std::string	className () const FL_IOVERRIDE
	Returns the name of the class of the term. More...

virtual std::string	parameters () const FL_IOVERRIDE
	Returns the parameters of the term as `formula` More...

virtual void	configure (const std::string &parameters) FL_IOVERRIDE
	Configures the term with the parameters given as `formula` More...

virtual void	setFormula (const std::string &formula)
	Sets the formula of the function. More...

virtual std::string	getFormula () const
	Gets the formula of the function. More...

virtual void	setEngine (const Engine *engine)
	Sets the engine to which the formula can refer. More...

virtual const Engine *	getEngine () const
	Gets the engine to which the formula can refer. More...

virtual Node *	root () const
	Gets the root node of the expression tree defining the Function. More...

virtual bool	isLoaded () const
	Indicates whether the formula is loaded. More...

virtual void	unload ()
	Unloads the formula and resets the map of substitution variables. More...

virtual void	load ()
	Loads the current formula expressed in infix notation. More...

virtual void	load (const std::string &formula)
	Loads the given formula expressed in infix notation. More...

virtual void	load (const std::string &formula, const Engine *engine)
	Loads the given formula expressed in infix notation, and sets the engine holding the variables to which the formula refers. More...

virtual Node *	parse (const std::string &formula)
	Creates a node representing a binary expression tree from the given formula. More...

virtual std::string	toPostfix (const std::string &formula) const
	Translates the given formula to postfix notation. More...

virtual std::string	space (const std::string &formula) const
	Adds spaces to the formula to separate parentheses, commas and function operators such that these are treated as tokens when parsing the function. More...

virtual void	updateReference (const Engine *engine) FL_IOVERRIDE
	Updates the references (if any) to point to the current engine (useful when cloning engines or creating terms within Importer objects. More...

virtual Function *	clone () const FL_IOVERRIDE
	Creates a clone of the term. More...

Public Member Functions inherited from fl::Term
	Term (const std::string &name="", scalar height=1.0)

virtual	~Term ()

virtual void	setName (const std::string &name)
	Sets the name of the term. More...

virtual std::string	getName () const
	Gets the name of the term. More...

virtual void	setHeight (scalar height)
	Sets the height of the term. More...

virtual scalar	getHeight () const
	Gets the height of the term. More...

virtual std::string	toString () const
	Returns the representation of the term in the FuzzyLite Language. More...

Static Public Member Functions
static Function *	create (const std::string &name, const std::string &formula, const Engine *engine=fl::null)
	Creates a Function term with the given parameters. More...

static Term *	constructor ()

Public Attributes
std::map< std::string, scalar >	variables
	A map of variables and substitution values. More...

Additional Inherited Members
Protected Attributes inherited from fl::Term
scalar	_height

Detailed Description

The Function class is a polynomial Term that represents a generic function \( f : x \mapsto f(x) \).

Every Function object has a public key-value map, namely Function::variables, that links variable names to fl::scalar values, which are utilized to replace the variable names for their respective values in the given formula whenever the function \(f\) is evaluated. Specifically, when the method Function::membership() is called, the name and value of the variable \(x\) are automatically loaded into the map. Furthermore, if an Engine is given, the names of its InputVariables and OutputVariables will also be automatically loaded into the map linking to their respective input values and (previously defuzzified) output values. The Function::variables need to be manually loaded whenever variables other than \(x\), input variables, and output variables, are expressed in the given formula, always having in mind that (a) the map replaces existing keys, and (b) the variable \(x\), and input variables and output variables of an engine will automatically be replaced and will also take precedence over previously loaded variables.

Besides the use of Function as a linguistic Term, it is also utilized to convert the text of the Antecedent of a Rule, expressed in infix notation, into postfix notation.

Author: Juan Rada-Vilela, Ph.D.

See also: Term; Variable; FunctionFactory; Antecedent::load()

Since: 4.0

Definition at line 60 of file Function.h.

Member Typedef Documentation

◆ Binary

typedef scalar(* fl::Function::Binary) (scalar, scalar)

Definition at line 63 of file Function.h.

◆ Unary

typedef scalar(* fl::Function::Unary) (scalar)

Definition at line 62 of file Function.h.

Constructor & Destructor Documentation

◆ Function() [1/2]

fl::Function::Function	(	const std::string &	name = `""`,
		const std::string &	formula = `""`,
		const Engine *	engine = `fl::null`
	)

explicit

◆ Function() [2/2]

fl::Function::Function ( const Function & other )

◆ ~Function()

virtual fl::Function::~Function ( )

virtual

Member Function Documentation

◆ className()

virtual std::string fl::Function::className ( ) const

virtual

Returns the name of the class of the term.

Returns: the name of the class of the term

Implements fl::Term.

◆ clone()

virtual Function* fl::Function::clone ( ) const

virtual

Creates a clone of the term.

Returns: a clone of the term

Implements fl::Term.

◆ complexity()

virtual Complexity fl::Function::complexity ( ) const

virtual

Computes the estimated complexity of evaluating the membership function.

Returns: the estimated complexity of evaluating the membership function

Implements fl::Term.

◆ configure()

virtual void fl::Function::configure ( const std::string & parameters )

virtual

Configures the term with the parameters given as formula

Parameters

parameters as formula

Implements fl::Term.

◆ constructor()

static Term* fl::Function::constructor ( )

static

◆ create()

static Function* fl::Function::create	(	const std::string &	name,
		const std::string &	formula,
		const Engine *	engine = `fl::null`
	)

static

Creates a Function term with the given parameters.

Parameters

name	is the name of the term
formula	is the formula defining the membership function
engine	is the engine to which the Function can have access

Returns: a Function term configured with the given parameters

Exceptions

fl::Exception if the formula has a syntax error

◆ evaluate()

virtual scalar fl::Function::evaluate ( const std::map< std::string, scalar > * variables = fl::null ) const

virtual

Computes the function value of this term using the given map of variable substitutions.

Parameters

variables is a map of substitution variables

Returns: the function value of this term using the given map of variable substitutions.

◆ getEngine()

virtual const Engine* fl::Function::getEngine ( ) const

virtual

Gets the engine to which the formula can refer.

Returns: the engine to which the formula can refer

◆ getFormula()

virtual std::string fl::Function::getFormula ( ) const

virtual

Gets the formula of the function.

Returns: the formula of the function

◆ isLoaded()

virtual bool fl::Function::isLoaded ( ) const

virtual

Indicates whether the formula is loaded.

Returns: whether the formula is loaded

◆ load() [1/3]

virtual void fl::Function::load ( )

virtual

Loads the current formula expressed in infix notation.

◆ load() [2/3]

virtual void fl::Function::load ( const std::string & formula )

virtual

Loads the given formula expressed in infix notation.

Parameters

formula is the right-hand side of a mathematical equation

Exceptions

fl::Exception if the formula has syntax errors

◆ load() [3/3]

virtual void fl::Function::load	(	const std::string &	formula,
		const Engine *	engine
	)

virtual

Loads the given formula expressed in infix notation, and sets the engine holding the variables to which the formula refers.

Parameters

formula	is the right-hand side of a mathematical equation expressed in infix notation
engine	is the engine to which the formula can refer

Exceptions

fl::Exception if the formula has syntax errors

◆ membership()

virtual scalar fl::Function::membership ( scalar x ) const

virtual

Computes the membership function value of \(x\) at the root node.

If the engine has been set, the current values of the input variables and output variables are added to the map of Function::variables. In addition, the variable \(x\) will also be added to the map.

Parameters

x

Returns: the membership function value of \(x\) at the root node

Implements fl::Term.

◆ operator=()

Function& fl::Function::operator= ( const Function & other )

◆ parameters()

virtual std::string fl::Function::parameters ( ) const

virtual

Returns the parameters of the term as formula

Returns: formula

Implements fl::Term.

◆ parse()

virtual Node* fl::Function::parse ( const std::string & formula )

virtual

Creates a node representing a binary expression tree from the given formula.

Parameters

formula is the right-hand side of a mathematical equation expressed in infix notation

Returns: a node representing a binary expression tree from the given formula

Exceptions

fl::Exception if the formula has syntax errors

◆ root()

virtual Node* fl::Function::root ( ) const

virtual

Gets the root node of the expression tree defining the Function.

The root is fl::null if the formula has not been loaded.

Returns: the root node of the expression tree defining the Function, or fl::null if the formula has not been loaded

◆ setEngine()

virtual void fl::Function::setEngine ( const Engine * engine )

virtual

Sets the engine to which the formula can refer.

Parameters

engine is the engine to which the formula can refer

◆ setFormula()

virtual void fl::Function::setFormula ( const std::string & formula )

virtual

Sets the formula of the function.

Parameters

formula is the formula of the function

◆ space()

virtual std::string fl::Function::space ( const std::string & formula ) const

virtual

Adds spaces to the formula to separate parentheses, commas and function operators such that these are treated as tokens when parsing the function.

Parameters

formula is the right-hand side of a mathematical equation expressed in infix notation

Returns: the formula with spaces before and after parentheses, commas and function operators

◆ toPostfix()

virtual std::string fl::Function::toPostfix ( const std::string & formula ) const

virtual

Translates the given formula to postfix notation.

Parameters

formula is the right-hand side of a mathematical equation expressed in infix notation

Returns: the formula represented in postfix notation

Exceptions

fl::Exception if the formula has syntax errors

◆ unload()

virtual void fl::Function::unload ( )

virtual

Unloads the formula and resets the map of substitution variables.

◆ updateReference()

virtual void fl::Function::updateReference ( const Engine * engine )

virtual

Updates the references (if any) to point to the current engine (useful when cloning engines or creating terms within Importer objects.

Parameters

engine is the engine to which this term belongs to

Reimplemented from fl::Term.

Member Data Documentation

◆ variables

std::map<std::string, scalar> fl::Function::variables

mutable

A map of variables and substitution values.

Definition at line 250 of file Function.h.

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

fuzzylite/fl/term/Function.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ Binary

◆ Unary

Constructor & Destructor Documentation

◆ Function() [1/2]

◆ Function() [2/2]

◆ ~Function()

Member Function Documentation

◆ className()

◆ clone()

◆ complexity()

◆ configure()

◆ constructor()

◆ create()

◆ evaluate()

◆ getEngine()

◆ getFormula()

◆ isLoaded()

◆ load() [1/3]

◆ load() [2/3]

◆ load() [3/3]

◆ membership()

◆ operator=()

◆ parameters()

◆ parse()

◆ root()

◆ setEngine()

◆ setFormula()

◆ space()

◆ toPostfix()

◆ unload()

◆ updateReference()

Member Data Documentation

◆ variables