Variable Class Reference

Detailed Description

Represents a symbolic variable.

Note

Expression::Evaluate and Formula::Evaluate methods take a symbolic environment (Variable → double) and a random number generator. When an expression or a formula includes random variables, Evaluate methods use the random number generator to draw a number for a random variable from the given distribution. Then this numeric value is used to substitute all the occurrences of the corresponding random variable in an expression or a formula.

#include <drake/common/symbolic/expression/variable.h>

Public Types
enum class	Type : uint8_t {   CONTINUOUS , INTEGER , BINARY , BOOLEAN ,   RANDOM_UNIFORM , RANDOM_GAUSSIAN , RANDOM_EXPONENTIAL }
	Supported types of symbolic variables. More...
typedef size_t	Id

Public Member Functions
	Variable ()=default
	Constructs a default variable of type CONTINUOUS with an Id of zero.
	Variable (std::nullptr_t)
	Constructs a default value.
	Variable (std::string name, Type type=Type::CONTINUOUS)
	Constructs a variable with a string.
	~Variable ()=default
bool	is_dummy () const
	Checks if this is the variable created by the default constructor.
Id	get_id () const
Type	get_type () const
std::string	get_name () const
std::string	to_string () const
bool	equal_to (const Variable &v) const
	Checks the equality of two variables based on their ID values.
bool	less (const Variable &v) const
	Compares two variables based on their ID values.
Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable
	Variable (const Variable &)=default
Variable &	operator= (const Variable &)=default
	Variable (Variable &&)=default
Variable &	operator= (Variable &&)=default

Friends
template<class HashAlgorithm>
void	hash_append (HashAlgorithm &hasher, const Variable &item) noexcept
	Implements the hash_append generic hashing concept.
std::ostream &	operator<< (std::ostream &os, const Variable &var)

Member Typedef Documentation

Id

typedef size_t Id

Member Enumeration Documentation

Type

enum class Type : uint8_t

strong

Supported types of symbolic variables.

Enumerator
CONTINUOUS	A CONTINUOUS variable takes a double value.
INTEGER	An INTEGER variable takes an int value.
BINARY	A BINARY variable takes an integer value from {0, 1}.
BOOLEAN	A BOOLEAN variable takes a bool value.
RANDOM_UNIFORM	A random variable whose value will be drawn from uniform real distributed ∈ [0,1).
RANDOM_GAUSSIAN	A random variable whose value will be drawn from mean-zero, unit-variance normal.
RANDOM_EXPONENTIAL	A random variable whose value will be drawn from exponential distribution with λ=1.

Constructor & Destructor Documentation

Variable() [1/5]

Variable ( const Variable & )

default

Variable() [2/5]

Variable ( Variable && )

default

Variable() [3/5]

Variable ( )

default

Constructs a default variable of type CONTINUOUS with an Id of zero.

All default-constructed variables are considered the same variable by the equality operator (==). Similarly, a moved-from variable is also identical to a default-constructed variable (in both its name and its Id).

Variable() [4/5]

Variable ( std::nullptr_t )

explicit

Constructs a default value.

This overload is used by Eigen when EIGEN_INITIALIZE_MATRICES_BY_ZERO is enabled.

Variable() [5/5]

Variable ( std::string name, Type type = Type::CONTINUOUS )

explicit

Constructs a variable with a string.

If not specified, it has CONTINUOUS type by default.

~Variable()

~Variable ( )

default

Member Function Documentation

equal_to()

bool equal_to ( const Variable & v ) const

nodiscard

Checks the equality of two variables based on their ID values.

get_id()

Id get_id ( ) const

nodiscard

get_name()

std::string get_name ( ) const

nodiscard

get_type()

Type get_type ( ) const

nodiscard

is_dummy()

bool is_dummy ( ) const

nodiscard

Checks if this is the variable created by the default constructor.

less()

bool less ( const Variable & v ) const

nodiscard

Compares two variables based on their ID values.

operator=() [1/2]

Variable & operator= ( const Variable & )

default

operator=() [2/2]

Variable & operator= ( Variable && )

default

to_string()

std::string to_string ( ) const

nodiscard

Friends And Related Symbol Documentation

hash_append

template<class HashAlgorithm>

void hash_append ( HashAlgorithm & hasher, const Variable & item )

friend

Implements the hash_append generic hashing concept.

operator<<

std::ostream & operator<< ( std::ostream & os, const Variable & var )

friend

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

• drake/common/symbolic/expression/variable.h