vita::function Class Reference

A symbol with arity() > 0. More...

#include <function.h>

Inherits vita::symbol.

Inherited by vita::boolean::l_and, vita::boolean::l_not, vita::boolean::l_or, vita::integer::add, vita::integer::div, vita::integer::ife, vita::integer::ifl, vita::integer::ifz, vita::integer::mod, vita::integer::mul, vita::integer::shl, vita::integer::sub, vita::real::abs, vita::real::add, vita::real::aq, vita::real::cos, vita::real::div, vita::real::gt, vita::real::idiv, vita::real::ifb, vita::real::ife, vita::real::ifl, vita::real::ifz, vita::real::length, vita::real::ln, vita::real::lt, vita::real::max, vita::real::mod, vita::real::mul, vita::real::sigmoid, vita::real::sin, vita::real::sqrt, vita::real::sub, and vita::str::ife.

Public Member Functions
category_t	arg_category (std::size_t) const
unsigned	arity () const final
virtual bool	associative () const
	Is the symbol subject to the associative law of arithmetic? More...
virtual std::string	display (format=c_format) const
	function (const std::string &, category_t, cvect)
	function (const std::string &, std::size_t)
bool	is_valid () const override
Public Member Functions inherited from vita::symbol
virtual unsigned	arity () const =0
category_t	category () const
	The type (a.k.a. More...
void	category (category_t)
	Changes the category of a symbol. More...
virtual value_t	eval (symbol_params &) const =0
	Calculates the value of / performs the action associated with the symbol (it's implementation specific). More...
virtual bool	input () const
	An input variable is a feature from the learning domain. More...
virtual bool	is_valid () const
std::string	name () const
opcode_t	opcode () const
	An opcode is a unique, numerical session ID for a symbol. More...
double	penalty (core_interpreter *) const
	Used for automatic calculation of penalities due to broken constraints. More...
	symbol (const std::string &, category_t=0)
bool	terminal () const

Static Public Member Functions
static const function *	cast (const symbol *)
	This is a short cut function. More...

Additional Inherited Members
Public Types inherited from vita::symbol
enum	format {   c_format , cpp_format , mql_format , python_format ,   sup_format }
	Symbol rendering format. More...

Detailed Description

A symbol with arity() > 0.

A function labels the internal (non-leaf) points of the parse trees that represent the programs in the population. An example function set might be {+, -, *}.

Warning

Each function should be able to handle gracefully all values it might receive as input (this is called closure property). If there is a way to crash the system, the GP system will certainly hit upon hit.

Definition at line 34 of file function.h.

Constructor & Destructor Documentation

function() [1/2]

vita::function::function	(	const std::string &	dis,
		category_t	c,
		cvect	args
	)

Parameters

[in]	dis	string representation of the function (e.g. for the plus function it could by "ADD" or "+")
[in]	c	category of the function (i.e. the category of the output value)
[in]	args	input parameters (type and number) of the function (in C++ they are called the "function signature")

Definition at line 25 of file function.cc.

function() [2/2]

vita::function::function	(	const std::string &	dis,
		std::size_t	n_args
	)

Parameters

[in]	dis	string representation of the function (e.g. for the plus function it could by "ADD" or "+")
[in]	n_args	number of arguments of the function

Assumes category 0 for the function and its arguments. This constructor is usually chosen when types are not used.

Definition at line 39 of file function.cc.

Member Function Documentation

arg_category()

category_t vita::function::arg_category ( std::size_t  i ) const

inline

Parameters

[in]

i

index of a function argument

Returns

category of the i-th function argument

Definition at line 89 of file function.h.

arity()

unsigned vita::function::arity ( ) const

inlinefinalvirtual

Returns

the number arguments of a funtion

Implements vita::symbol.

Definition at line 59 of file function.h.

associative()

bool vita::function::associative ( ) const

inlinevirtual

Is the symbol subject to the associative law of arithmetic?

Returns

true if the function is associative

OP is associative iff:

a OP (b OP c) = (a OP b) OP c = a OP b OP c

This information can be used for optimization and visualization.

Note

• Terminals haven't arguments and cannot be associative.
• Default (safe) value is false.

Reimplemented in vita::boolean::l_and, vita::boolean::l_or, vita::integer::add, vita::integer::mul, and vita::real::add.

Definition at line 80 of file function.h.

cast()

const function * vita::function::cast ( const symbol *  s )

inlinestatic

This is a short cut function.

Parameters

[in]

s

symbol pointer

Returns

s casted to a vita::function pointer

Definition at line 101 of file function.h.

display()

std::string vita::function::display ( format  = c_format ) const

virtual

Returns

the name of the function

Warning

Specific functions have to specialize this method to support different output formats.

Reimplemented in vita::boolean::l_and, vita::boolean::l_not, vita::boolean::l_or, vita::real::abs, vita::real::aq, vita::real::cos, vita::real::gt, vita::real::idiv, vita::real::ifb, vita::real::ife, vita::real::ifl, vita::real::ifz, vita::real::length, vita::real::ln, vita::real::lt, vita::real::max, vita::real::mod, vita::real::sin, vita::real::sqrt, vita::real::sigmoid, vita::str::ife, vita::real::add, vita::real::div, vita::real::mul, and vita::real::sub.

Definition at line 52 of file function.cc.

is_valid()

bool vita::function::is_valid ( ) const

overridevirtual

Returns

true if the object passes the internal consistency check

Reimplemented from vita::symbol.

Definition at line 64 of file function.cc.

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

• function.h
• function.cc