Detailed Description

Represents a symbolic form of an expression.

Its syntax tree is as follows:

    E := Var | Constant | E + ... + E | E * ... * E | E / E | log(E)
       | abs(E) | exp(E) | sqrt(E) | pow(E, E) | sin(E) | cos(E) | tan(E)
       | asin(E) | acos(E) | atan(E) | atan2(E, E) | sinh(E) | cosh(E) | tanh(E)
       | min(E, E) | max(E, E) | ceil(E) | floor(E) | if_then_else(F, E, E)
       | NaN | uninterpreted_function(name, {v_1, ..., v_n})

In the implementation, Expression directly stores Constant values inline, but in all other cases stores a shared pointer to a const ExpressionCell class that is a super-class of different kinds of symbolic expressions (i.e., ExpressionAdd, ExpressionMul, ExpressionLog, ExpressionSin), which makes it efficient to copy, move, and assign to an Expression.

Note: -E is represented as -1 * E internally.; A subtraction E1 - E2 is represented as E1 + (-1 * E2) internally.

The following simple simplifications are implemented:

    E + 0             ->  E
    0 + E             ->  E
    E - 0             ->  E
    E - E             ->  0
    E * 1             ->  E
    1 * E             ->  E
    E * 0             ->  0
    0 * E             ->  0
    E / 1             ->  E
    E / E             ->  1
    pow(E, 0)         ->  1
    pow(E, 1)         ->  E
    E * E             ->  E^2 (= pow(E, 2))
    sqrt(E * E)       ->  |E| (= abs(E))
    sqrt(E) * sqrt(E) -> E

Constant folding is implemented:

    E(c1) + E(c2)  ->  E(c1 + c2)    // c1, c2 are constants
    E(c1) - E(c2)  ->  E(c1 - c2)
    E(c1) * E(c2)  ->  E(c1 * c2)
    E(c1) / E(c2)  ->  E(c1 / c2)
    f(E(c))        ->  E(f(c))       // c is a constant, f is a math function

For the math functions which are only defined over a restricted domain (namely, log, sqrt, pow, asin, acos), we check the domain of argument(s), and throw std::domain_error exception if a function is not well-defined for a given argument(s).

Relational operators over expressions (==, !=, <, >, <=, >=) return symbolic::Formula instead of bool. Those operations are declared in formula.h file. To check structural equality between two expressions a separate function, Expression::EqualTo, is provided.

Regarding the arithmetic of an Expression when operating on NaNs, we have the following rules:

NaN values are extremely rare during typical computations. Because they are difficult to handle symbolically, we will round that up to "must never occur". We allow the user to form ExpressionNaN cells in a symbolic tree. For example, the user can initialize an Expression to NaN and then overwrite it later. However, evaluating a tree that has NaN in its evaluated sub-trees is an error (see rule (3) below).
It's still valid for code to check isnan in order to fail-fast. So we provide isnan(const Expression&) for the common case of non-NaN value returning False. This way, code can fail-fast with double yet still compile with Expression.
If there are expressions that embed separate cases (if_then_else), some of the sub-expressions may be not used in evaluation when they are in the not-taken case (for NaN reasons or any other reason). Bad values within those not-taken branches does not cause exceptions.
The isnan check is different than if_then_else. In the latter, the ExpressionNaN is within a dead sub-expression branch. In the former, it appears in an evaluated trunk. That goes against rule (1) where a NaN anywhere in a computation (other than dead code) is an error.

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

Public Member Functions
	~Expression ()=default

	Expression ()=default
	Default constructor. More...

	Expression (double constant)
	Constructs a constant. More...

	Expression (const Variable &var)
	Constructs an expression from `var`. More...

ExpressionKind	get_kind () const
	Returns expression kind. More...

Variables	GetVariables () const
	Collects variables in expression. More...

bool	EqualTo (const Expression &e) const
	Checks structural equality. More...

bool	Less (const Expression &e) const
	Provides lexicographical ordering between expressions. More...

bool	is_polynomial () const
	Checks if this symbolic expression is convertible to Polynomial. More...

double	Evaluate (const Environment &env=Environment{}, RandomGenerator *random_generator=nullptr) const
	Evaluates using a given environment (by default, an empty environment) and a random number generator. More...

double	Evaluate (RandomGenerator *random_generator) const
	Evaluates using an empty environment and a random number generator. More...

Expression	EvaluatePartial (const Environment &env) const
	Partially evaluates this expression using an environment `env`. More...

bool	is_expanded () const
	Returns true if this symbolic expression is already expanded. More...

Expression	Expand () const
	Expands out products and positive integer powers in expression. More...

Expression	Substitute (const Variable &var, const Expression &e) const
	Returns a copy of this expression replacing all occurrences of `var` with `e`. More...

Expression	Substitute (const Substitution &s) const
	Returns a copy of this expression replacing all occurrences of the variables in `s` with corresponding expressions in `s`. More...

Expression	Differentiate (const Variable &x) const
	Differentiates this symbolic expression with respect to the variable `var`. More...

RowVectorX< Expression >	Jacobian (const Eigen::Ref< const VectorX< Variable >> &vars) const
	Let `f` be this Expression, computes a row vector of derivatives, `[∂f/∂vars(0), ...` More...

std::string	to_string () const
	Returns string representation of Expression. More...

Expression &	operator++ ()
	Provides prefix increment operator (i.e. More...

Expression	operator++ (int)
	Provides postfix increment operator (i.e. More...

Expression &	operator-- ()
	Provides prefix decrement operator (i.e. More...

Expression	operator-- (int)
	Provides postfix decrement operator (i.e. More...

Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable
	Expression (const Expression &)=default

Expression &	operator= (const Expression &)=default

	Expression (Expression &&)=default

Expression &	operator= (Expression &&)=default

Static Public Member Functions
static Expression	Zero ()
	Returns zero. More...

static Expression	One ()
	Returns one. More...

static Expression	Pi ()
	Returns Pi, the ratio of a circle’s circumference to its diameter. More...

static Expression	E ()
	Return e, the base of natural logarithms. More...

static Expression	NaN ()
	Returns NaN (Not-a-Number). More...

Friends
class	ExpressionAddFactory

class	ExpressionMulFactory

template<bool >
struct	internal::Gemm

template<class HashAlgorithm >
void	hash_append (HashAlgorithm &hasher, const Expression &item) noexcept
	Implements the hash_append generic hashing concept. More...

Expression	operator+ (Expression lhs, const Expression &rhs)

Expression &	operator+= (Expression &lhs, const Expression &rhs)

Expression	operator+ (const Expression &e)
	Provides unary plus operator. More...

Expression	operator- (Expression lhs, const Expression &rhs)

Expression &	operator-= (Expression &lhs, const Expression &rhs)

Expression	operator- (const Expression &e)
	Provides unary minus operator. More...

Expression	operator * (Expression lhs, const Expression &rhs)

Expression &	operator *= (Expression &lhs, const Expression &rhs)

Expression	operator/ (Expression lhs, const Expression &rhs)

Expression &	operator/= (Expression &lhs, const Expression &rhs)

Expression	log (const Expression &e)

Expression	abs (const Expression &e)

Expression	exp (const Expression &e)

Expression	sqrt (const Expression &e)

Expression	pow (const Expression &e1, const Expression &e2)

Expression	sin (const Expression &e)

Expression	cos (const Expression &e)

Expression	tan (const Expression &e)

Expression	asin (const Expression &e)

Expression	acos (const Expression &e)

Expression	atan (const Expression &e)

Expression	atan2 (const Expression &e1, const Expression &e2)

Expression	sinh (const Expression &e)

Expression	cosh (const Expression &e)

Expression	tanh (const Expression &e)

Expression	min (const Expression &e1, const Expression &e2)

Expression	max (const Expression &e1, const Expression &e2)

Expression	clamp (const Expression &v, const Expression &lo, const Expression &hi)

Expression	ceil (const Expression &e)

Expression	floor (const Expression &e)

Expression	if_then_else (const Formula &f_cond, const Expression &e_then, const Expression &e_else)
	Constructs if-then-else expression. More...

Expression	uninterpreted_function (std::string name, std::vector< Expression > arguments)
	Constructs an uninterpreted-function expression with `name` and `arguments`. More...

std::ostream &	operator<< (std::ostream &os, const Expression &e)

void	swap (Expression &a, Expression &b)

bool	is_constant (const Expression &e)
	Checks if `e` is a constant expression. More...

bool	is_constant (const Expression &e, double value)
	Checks if `e` is a constant expression representing `v`. More...

bool	is_nan (const Expression &e)
	Checks if `e` is NaN. More...

bool	is_variable (const Expression &e)
	Checks if `e` is a variable expression. More...

bool	is_addition (const Expression &e)
	Checks if `e` is an addition expression. More...

bool	is_multiplication (const Expression &e)
	Checks if `e` is a multiplication expression. More...

bool	is_division (const Expression &e)
	Checks if `e` is a division expression. More...

bool	is_log (const Expression &e)
	Checks if `e` is a log expression. More...

bool	is_abs (const Expression &e)
	Checks if `e` is an abs expression. More...

bool	is_exp (const Expression &e)
	Checks if `e` is an exp expression. More...

bool	is_sqrt (const Expression &e)
	Checks if `e` is a square-root expression. More...

bool	is_pow (const Expression &e)
	Checks if `e` is a power-function expression. More...

bool	is_sin (const Expression &e)
	Checks if `e` is a sine expression. More...

bool	is_cos (const Expression &e)
	Checks if `e` is a cosine expression. More...

bool	is_tan (const Expression &e)
	Checks if `e` is a tangent expression. More...

bool	is_asin (const Expression &e)
	Checks if `e` is an arcsine expression. More...

bool	is_acos (const Expression &e)
	Checks if `e` is an arccosine expression. More...

bool	is_atan (const Expression &e)
	Checks if `e` is an arctangent expression. More...

bool	is_atan2 (const Expression &e)
	Checks if `e` is an arctangent2 expression. More...

bool	is_sinh (const Expression &e)
	Checks if `e` is a hyperbolic-sine expression. More...

bool	is_cosh (const Expression &e)
	Checks if `e` is a hyperbolic-cosine expression. More...

bool	is_tanh (const Expression &e)
	Checks if `e` is a hyperbolic-tangent expression. More...

bool	is_min (const Expression &e)
	Checks if `e` is a min expression. More...

bool	is_max (const Expression &e)
	Checks if `e` is a max expression. More...

bool	is_ceil (const Expression &e)
	Checks if `e` is a ceil expression. More...

bool	is_floor (const Expression &e)
	Checks if `e` is a floor expression. More...

bool	is_if_then_else (const Expression &e)
	Checks if `e` is an if-then-else expression. More...

bool	is_uninterpreted_function (const Expression &e)
	Checks if `e` is an uninterpreted-function expression. More...

double	get_constant_value (const Expression &e)
	Returns the constant value of the constant expression `e`. More...

const ExpressionVar &	to_variable (const Expression &e)

const UnaryExpressionCell &	to_unary (const Expression &e)

const BinaryExpressionCell &	to_binary (const Expression &e)

const ExpressionAdd &	to_addition (const Expression &e)

const ExpressionMul &	to_multiplication (const Expression &e)

const ExpressionDiv &	to_division (const Expression &e)

const ExpressionLog &	to_log (const Expression &e)

const ExpressionAbs &	to_abs (const Expression &e)

const ExpressionExp &	to_exp (const Expression &e)

const ExpressionSqrt &	to_sqrt (const Expression &e)

const ExpressionPow &	to_pow (const Expression &e)

const ExpressionSin &	to_sin (const Expression &e)

const ExpressionCos &	to_cos (const Expression &e)

const ExpressionTan &	to_tan (const Expression &e)

const ExpressionAsin &	to_asin (const Expression &e)

const ExpressionAcos &	to_acos (const Expression &e)

const ExpressionAtan &	to_atan (const Expression &e)

const ExpressionAtan2 &	to_atan2 (const Expression &e)

const ExpressionSinh &	to_sinh (const Expression &e)

const ExpressionCosh &	to_cosh (const Expression &e)

const ExpressionTanh &	to_tanh (const Expression &e)

const ExpressionMin &	to_min (const Expression &e)

const ExpressionMax &	to_max (const Expression &e)

const ExpressionCeiling &	to_ceil (const Expression &e)

const ExpressionFloor &	to_floor (const Expression &e)

const ExpressionIfThenElse &	to_if_then_else (const Expression &e)

const ExpressionUninterpretedFunction &	to_uninterpreted_function (const Expression &e)

ExpressionVar &	to_variable (Expression *e)

UnaryExpressionCell &	to_unary (Expression *e)

BinaryExpressionCell &	to_binary (Expression *e)

ExpressionAdd &	to_addition (Expression *e)

ExpressionMul &	to_multiplication (Expression *e)

ExpressionDiv &	to_division (Expression *e)

ExpressionLog &	to_log (Expression *e)

ExpressionAbs &	to_abs (Expression *e)

ExpressionExp &	to_exp (Expression *e)

ExpressionSqrt &	to_sqrt (Expression *e)

ExpressionPow &	to_pow (Expression *e)

ExpressionSin &	to_sin (Expression *e)

ExpressionCos &	to_cos (Expression *e)

ExpressionTan &	to_tan (Expression *e)

ExpressionAsin &	to_asin (Expression *e)

ExpressionAcos &	to_acos (Expression *e)

ExpressionAtan &	to_atan (Expression *e)

ExpressionAtan2 &	to_atan2 (Expression *e)

ExpressionSinh &	to_sinh (Expression *e)

ExpressionCosh &	to_cosh (Expression *e)

ExpressionTanh &	to_tanh (Expression *e)

ExpressionMin &	to_min (Expression *e)

ExpressionMax &	to_max (Expression *e)

ExpressionCeiling &	to_ceil (Expression *e)

ExpressionFloor &	to_floor (Expression *e)

ExpressionIfThenElse &	to_if_then_else (Expression *e)

ExpressionUninterpretedFunction &	to_uninterpreted_function (Expression *e)

Constructor & Destructor Documentation

◆ Expression() [1/5]

Expression ( const Expression & )

default

◆ Expression() [2/5]

Expression ( Expression && )

default

◆ ~Expression()

~Expression ( )

default

◆ Expression() [3/5]

Expression ( )

default

Default constructor.

It constructs Zero().

◆ Expression() [4/5]

Expression ( double constant )

Constructs a constant.

◆ Expression() [5/5]

Expression ( const Variable & var )

Constructs an expression from var.

Precondition: var is not a BOOLEAN variable.

Member Function Documentation

◆ Differentiate()

Expression Differentiate ( const Variable & x ) const

Differentiates this symbolic expression with respect to the variable var.

Exceptions

std::exception if it is not differentiable.

◆ E()

static Expression E ( )

static

Return e, the base of natural logarithms.

◆ EqualTo()

bool EqualTo ( const Expression & e ) const

Checks structural equality.

Two expressions e1 and e2 are structurally equal when they have the same internal AST(abstract-syntax tree) representation. Please note that we can have two computationally (or extensionally) equivalent expressions which are not structurally equal. For example, consider:

e1 = 2 * (x + y) e2 = 2x + 2y

Obviously, we know that e1 and e2 are evaluated to the same value for all assignments to x and y. However, e1 and e2 are not structurally equal by the definition. Note that e1 is a multiplication expression (is_multiplication(e1) is true) while e2 is an addition expression (is_addition(e2) is true).

One main reason we use structural equality in EqualTo is due to Richardson's Theorem. It states that checking ∀x. E(x) = F(x) is undecidable when we allow sin, asin, log, exp in E and F. Read https://en.wikipedia.org/wiki/Richardson%27s_theorem for details.

Note that for polynomial cases, you can use Expand method and check if two polynomial expressions p1 and p2 are computationally equal. To do so, you check the following:

p1.Expand().EqualTo(p2.Expand())

◆ Evaluate() [1/2]

double Evaluate	(	const Environment &	env = `Environment{}`,
		RandomGenerator *	random_generator = `nullptr`
	)		const

Evaluates using a given environment (by default, an empty environment) and a random number generator.

If there is a random variable in this expression which is unassigned in env, this method uses random_generator to sample a value and use the value to substitute all occurrences of the variable in this expression.

Exceptions

std::exception	if there exists a non-random variable in this expression whose assignment is not provided by `env`.
std::exception	if an unassigned random variable is detected while `random_generator` is `nullptr`.
std::exception	if NaN is detected during evaluation.

◆ Evaluate() [2/2]

double Evaluate ( RandomGenerator * random_generator ) const

Evaluates using an empty environment and a random number generator.

It uses random_generator to sample values for the random variables in this expression.

See the above overload for the exceptions that it might throw.

◆ EvaluatePartial()

Expression EvaluatePartial ( const Environment & env ) const

Partially evaluates this expression using an environment env.

Internally, this method promotes env into a substitution (Variable → Expression) and call Evaluate::Substitute with it.

Exceptions

std::exception if NaN is detected during evaluation.

◆ Expand()

Expression Expand ( ) const

Expands out products and positive integer powers in expression.

For example, (x + 1) * (x - 1) is expanded to x^2 - 1 and (x + y)^2 is expanded to x^2 + 2xy + y^2. Note that Expand applies recursively to sub-expressions. For instance, sin(2 * (x + y)) is expanded to sin(2x + 2y). It also simplifies "division by constant" cases. See "drake/common/test/symbolic_expansion_test.cc" to find the examples.

Exceptions

std::exception if NaN is detected during expansion.

◆ get_kind()

ExpressionKind get_kind ( ) const

Returns expression kind.

◆ GetVariables()

Variables GetVariables ( ) const

Collects variables in expression.

◆ is_expanded()

bool is_expanded ( ) const

Returns true if this symbolic expression is already expanded.

Expression::Expand() uses this flag to avoid calling ExpressionCell::Expand() on an pre-expanded expressions. Expression::Expand() also sets this flag before returning the result.

Note: This check is conservative in that false does not always indicate that the expression is not expanded. This is because exact checks can be costly and we want to avoid the exact check at the construction time.

◆ is_polynomial()

bool is_polynomial ( ) const

Checks if this symbolic expression is convertible to Polynomial.

◆ Jacobian()

RowVectorX<Expression> Jacobian ( const Eigen::Ref< const VectorX< Variable >> & vars ) const

Let f be this Expression, computes a row vector of derivatives, [∂f/∂vars(0), ...

, ∂f/∂vars(n-1)] with respect to the variables vars.

◆ Less()

bool Less ( const Expression & e ) const

Provides lexicographical ordering between expressions.

This function is used as a compare function in map<Expression> and set<Expression> via std::less<drake::symbolic::Expression>.

◆ NaN()

static Expression NaN ( )

static

Returns NaN (Not-a-Number).

◆ One()

static Expression One ( )

static

Returns one.

◆ operator++() [1/2]

Expression& operator++ ( )

Provides prefix increment operator (i.e.

++x).

◆ operator++() [2/2]

Expression operator++ ( int )

Provides postfix increment operator (i.e.

x++).

◆ operator--() [1/2]

Expression& operator-- ( )

Provides prefix decrement operator (i.e.

–x).

◆ operator--() [2/2]

Expression operator-- ( int )

Provides postfix decrement operator (i.e.

x–).

◆ operator=() [1/2]

Expression& operator= ( Expression && )

default

◆ operator=() [2/2]

Expression& operator= ( const Expression & )

default

◆ Pi()

static Expression Pi ( )

static

Returns Pi, the ratio of a circle’s circumference to its diameter.

◆ Substitute() [1/2]

Expression Substitute	(	const Variable &	var,
		const Expression &	e
	)		const

Returns a copy of this expression replacing all occurrences of var with e.

Exceptions

std::exception if NaN is detected during substitution.

◆ Substitute() [2/2]

Expression Substitute ( const Substitution & s ) const

Returns a copy of this expression replacing all occurrences of the variables in s with corresponding expressions in s.

Note that the substitutions occur simultaneously. For example, (x / y).Substitute({{x, y}, {y, x}}) gets (y / x).

Exceptions

std::exception if NaN is detected during substitution.

◆ to_string()

std::string to_string ( ) const

Returns string representation of Expression.

◆ Zero()

static Expression Zero ( )

static

Returns zero.

Friends And Related Function Documentation

◆ abs

Expression abs ( const Expression & e )

friend

◆ acos

Expression acos ( const Expression & e )

friend

◆ asin

Expression asin ( const Expression & e )

friend

◆ atan

Expression atan ( const Expression & e )

friend

◆ atan2

Expression atan2	(	const Expression &	e1,
		const Expression &	e2
	)

friend

◆ ceil

Expression ceil ( const Expression & e )

friend

◆ clamp

Expression clamp	(	const Expression &	v,
		const Expression &	lo,
		const Expression &	hi
	)

friend

◆ cos

Expression cos ( const Expression & e )

friend

◆ cosh

Expression cosh ( const Expression & e )

friend

◆ exp

Expression exp ( const Expression & e )

friend

◆ ExpressionAddFactory

friend class ExpressionAddFactory

friend

◆ ExpressionMulFactory

friend class ExpressionMulFactory

friend

◆ floor

Expression floor ( const Expression & e )

friend

◆ get_constant_value

double get_constant_value ( const Expression & e )

friend

Returns the constant value of the constant expression e.

Precondition: {e is a constant expression.}

◆ hash_append

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

friend

Implements the hash_append generic hashing concept.

◆ if_then_else

Expression if_then_else	(	const Formula &	f_cond,
		const Expression &	e_then,
		const Expression &	e_else
	)

friend

Constructs if-then-else expression.

  if_then_else(cond, expr_then, expr_else)

The value returned by the above if-then-else expression is expr_then if cond is evaluated to true. Otherwise, it returns expr_else.

The semantics is similar to the C++'s conditional expression constructed by its ternary operator, ?:. However, there is a key difference between the C++'s conditional expression and our if_then_else expression in a way the arguments are evaluated during the construction.

In case of the C++'s conditional expression, cond ? expr_then : expr_else, the then expression expr_then (respectively, the else expression expr_else) is only evaluated when the conditional expression cond is evaluated to true (respectively, when cond is evaluated to false).
In case of the symbolic expression, if_then_else(cond, expr_then, expr_else), however, both arguments expr_then and expr_else are evaluated first and then passed to the if_then_else function.

Note: This function returns an expression and it is different from the C++'s if-then-else statement.; While it is still possible to define min, max, abs math functions using if_then_else expression, it is highly recommended to use the provided native definitions for them because it allows solvers to detect specific math functions and to have a room for special optimizations.; More information about the C++'s conditional expression and ternary operator is available at http://en.cppreference.com/w/cpp/language/operator_other#Conditional_operator.

◆ internal::Gemm

friend struct internal::Gemm

friend

◆ is_abs

bool is_abs ( const Expression & e )

friend

Checks if e is an abs expression.

◆ is_acos

bool is_acos ( const Expression & e )

friend

Checks if e is an arccosine expression.

◆ is_addition

bool is_addition ( const Expression & e )

friend

Checks if e is an addition expression.

◆ is_asin

bool is_asin ( const Expression & e )

friend

Checks if e is an arcsine expression.

◆ is_atan

bool is_atan ( const Expression & e )

friend

Checks if e is an arctangent expression.

◆ is_atan2

bool is_atan2 ( const Expression & e )

friend

Checks if e is an arctangent2 expression.

◆ is_ceil

bool is_ceil ( const Expression & e )

friend

Checks if e is a ceil expression.

◆ is_constant [1/2]

bool is_constant ( const Expression & e )

friend

Checks if e is a constant expression.

◆ is_constant [2/2]

bool is_constant	(	const Expression &	e,
		double	value
	)

friend

Checks if e is a constant expression representing v.

◆ is_cos

bool is_cos ( const Expression & e )

friend

Checks if e is a cosine expression.

◆ is_cosh

bool is_cosh ( const Expression & e )

friend

Checks if e is a hyperbolic-cosine expression.

◆ is_division

bool is_division ( const Expression & e )

friend

Checks if e is a division expression.

◆ is_exp

bool is_exp ( const Expression & e )

friend

Checks if e is an exp expression.

◆ is_floor

bool is_floor ( const Expression & e )

friend

Checks if e is a floor expression.

◆ is_if_then_else

bool is_if_then_else ( const Expression & e )

friend

Checks if e is an if-then-else expression.

◆ is_log

bool is_log ( const Expression & e )

friend

Checks if e is a log expression.

◆ is_max

bool is_max ( const Expression & e )

friend

Checks if e is a max expression.

◆ is_min

bool is_min ( const Expression & e )

friend

Checks if e is a min expression.

◆ is_multiplication

bool is_multiplication ( const Expression & e )

friend

Checks if e is a multiplication expression.

◆ is_nan

bool is_nan ( const Expression & e )

friend

Checks if e is NaN.

◆ is_pow

bool is_pow ( const Expression & e )

friend

Checks if e is a power-function expression.

◆ is_sin

bool is_sin ( const Expression & e )

friend

Checks if e is a sine expression.

◆ is_sinh

bool is_sinh ( const Expression & e )

friend

Checks if e is a hyperbolic-sine expression.

◆ is_sqrt

bool is_sqrt ( const Expression & e )

friend

Checks if e is a square-root expression.

◆ is_tan

bool is_tan ( const Expression & e )

friend

Checks if e is a tangent expression.

◆ is_tanh

bool is_tanh ( const Expression & e )

friend

Checks if e is a hyperbolic-tangent expression.

◆ is_uninterpreted_function

bool is_uninterpreted_function ( const Expression & e )

friend

Checks if e is an uninterpreted-function expression.

◆ is_variable

bool is_variable ( const Expression & e )

friend

Checks if e is a variable expression.

◆ log

Expression log ( const Expression & e )

friend

◆ max

Expression max	(	const Expression &	e1,
		const Expression &	e2
	)

friend

◆ min

Expression min	(	const Expression &	e1,
		const Expression &	e2
	)

friend

◆ operator *

Expression operator *	(	Expression	lhs,
		const Expression &	rhs
	)

friend

◆ operator *=

Expression& operator *=	(	Expression &	lhs,
		const Expression &	rhs
	)

friend

◆ operator+ [1/2]

Expression operator+	(	Expression	lhs,
		const Expression &	rhs
	)

friend

◆ operator+ [2/2]

Expression operator+ ( const Expression & e )

friend

Provides unary plus operator.

◆ operator+=

Expression& operator+=	(	Expression &	lhs,
		const Expression &	rhs
	)

friend

◆ operator- [1/2]

Expression operator-	(	Expression	lhs,
		const Expression &	rhs
	)

friend

◆ operator- [2/2]

Expression operator- ( const Expression & e )

friend

Provides unary minus operator.

◆ operator-=

Expression& operator-=	(	Expression &	lhs,
		const Expression &	rhs
	)

friend

◆ operator/

Expression operator/	(	Expression	lhs,
		const Expression &	rhs
	)

friend

◆ operator/=

Expression& operator/=	(	Expression &	lhs,
		const Expression &	rhs
	)

friend

◆ operator<<

std::ostream& operator<<	(	std::ostream &	os,
		const Expression &	e
	)

friend

◆ pow

Expression pow	(	const Expression &	e1,
		const Expression &	e2
	)

friend

◆ sin

Expression sin ( const Expression & e )

friend

◆ sinh

Expression sinh ( const Expression & e )

friend

◆ sqrt

Expression sqrt ( const Expression & e )

friend

◆ swap

void swap	(	Expression &	a,
		Expression &	b
	)

friend

◆ tan

Expression tan ( const Expression & e )

friend

◆ tanh

Expression tanh ( const Expression & e )

friend

◆ to_abs [1/2]

const ExpressionAbs& to_abs ( const Expression & e )

friend

◆ to_abs [2/2]

ExpressionAbs& to_abs ( Expression * e )

friend

◆ to_acos [1/2]

const ExpressionAcos& to_acos ( const Expression & e )

friend

◆ to_acos [2/2]

ExpressionAcos& to_acos ( Expression * e )

friend

◆ to_addition [1/2]

const ExpressionAdd& to_addition ( const Expression & e )

friend

◆ to_addition [2/2]

ExpressionAdd& to_addition ( Expression * e )

friend

◆ to_asin [1/2]

const ExpressionAsin& to_asin ( const Expression & e )

friend

◆ to_asin [2/2]

ExpressionAsin& to_asin ( Expression * e )

friend

◆ to_atan [1/2]

const ExpressionAtan& to_atan ( const Expression & e )

friend

◆ to_atan [2/2]

ExpressionAtan& to_atan ( Expression * e )

friend

◆ to_atan2 [1/2]

const ExpressionAtan2& to_atan2 ( const Expression & e )

friend

◆ to_atan2 [2/2]

ExpressionAtan2& to_atan2 ( Expression * e )

friend

◆ to_binary [1/2]

const BinaryExpressionCell& to_binary ( const Expression & e )

friend

◆ to_binary [2/2]

BinaryExpressionCell& to_binary ( Expression * e )

friend

◆ to_ceil [1/2]

const ExpressionCeiling& to_ceil ( const Expression & e )

friend

◆ to_ceil [2/2]

ExpressionCeiling& to_ceil ( Expression * e )

friend

◆ to_cos [1/2]

const ExpressionCos& to_cos ( const Expression & e )

friend

◆ to_cos [2/2]

ExpressionCos& to_cos ( Expression * e )

friend

◆ to_cosh [1/2]

const ExpressionCosh& to_cosh ( const Expression & e )

friend

◆ to_cosh [2/2]

ExpressionCosh& to_cosh ( Expression * e )

friend

◆ to_division [1/2]

const ExpressionDiv& to_division ( const Expression & e )

friend

◆ to_division [2/2]

ExpressionDiv& to_division ( Expression * e )

friend

◆ to_exp [1/2]

const ExpressionExp& to_exp ( const Expression & e )

friend

◆ to_exp [2/2]

ExpressionExp& to_exp ( Expression * e )

friend

◆ to_floor [1/2]

const ExpressionFloor& to_floor ( const Expression & e )

friend

◆ to_floor [2/2]

ExpressionFloor& to_floor ( Expression * e )

friend

◆ to_if_then_else [1/2]

const ExpressionIfThenElse& to_if_then_else ( const Expression & e )

friend

◆ to_if_then_else [2/2]

ExpressionIfThenElse& to_if_then_else ( Expression * e )

friend

◆ to_log [1/2]

const ExpressionLog& to_log ( const Expression & e )

friend

◆ to_log [2/2]

ExpressionLog& to_log ( Expression * e )

friend

◆ to_max [1/2]

const ExpressionMax& to_max ( const Expression & e )

friend

◆ to_max [2/2]

ExpressionMax& to_max ( Expression * e )

friend

◆ to_min [1/2]

const ExpressionMin& to_min ( const Expression & e )

friend

◆ to_min [2/2]

ExpressionMin& to_min ( Expression * e )

friend

◆ to_multiplication [1/2]

const ExpressionMul& to_multiplication ( const Expression & e )

friend

◆ to_multiplication [2/2]

ExpressionMul& to_multiplication ( Expression * e )

friend

◆ to_pow [1/2]

const ExpressionPow& to_pow ( const Expression & e )

friend

◆ to_pow [2/2]

ExpressionPow& to_pow ( Expression * e )

friend

◆ to_sin [1/2]

const ExpressionSin& to_sin ( const Expression & e )

friend

◆ to_sin [2/2]

ExpressionSin& to_sin ( Expression * e )

friend

◆ to_sinh [1/2]

const ExpressionSinh& to_sinh ( const Expression & e )

friend

◆ to_sinh [2/2]

ExpressionSinh& to_sinh ( Expression * e )

friend

◆ to_sqrt [1/2]

const ExpressionSqrt& to_sqrt ( const Expression & e )

friend

◆ to_sqrt [2/2]

ExpressionSqrt& to_sqrt ( Expression * e )

friend

◆ to_tan [1/2]

const ExpressionTan& to_tan ( const Expression & e )

friend

◆ to_tan [2/2]

ExpressionTan& to_tan ( Expression * e )

friend

◆ to_tanh [1/2]

const ExpressionTanh& to_tanh ( const Expression & e )

friend

◆ to_tanh [2/2]

ExpressionTanh& to_tanh ( Expression * e )

friend

◆ to_unary [1/2]

const UnaryExpressionCell& to_unary ( const Expression & e )

friend

◆ to_unary [2/2]

UnaryExpressionCell& to_unary ( Expression * e )

friend

◆ to_uninterpreted_function [1/2]

const ExpressionUninterpretedFunction& to_uninterpreted_function ( const Expression & e )

friend

◆ to_uninterpreted_function [2/2]

ExpressionUninterpretedFunction& to_uninterpreted_function ( Expression * e )

friend

◆ to_variable [1/2]

const ExpressionVar& to_variable ( const Expression & e )

friend

◆ to_variable [2/2]

ExpressionVar& to_variable ( Expression * e )

friend

◆ uninterpreted_function

Expression uninterpreted_function	(	std::string	name,
		std::vector< Expression >	arguments
	)

friend

Constructs an uninterpreted-function expression with name and arguments.

An uninterpreted function is an opaque function that has no other property than its name and a list of its arguments. This is useful to applications where it is good enough to provide abstract information of a function without exposing full details. Declaring sparsity of a system is a typical example.

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

drake/common/symbolic/expression/expression.h

Detailed Description

Public Member Functions

Static Public Member Functions

Friends

Constructor & Destructor Documentation

◆ Expression() [1/5]

◆ Expression() [2/5]

◆ ~Expression()

◆ Expression() [3/5]

◆ Expression() [4/5]

◆ Expression() [5/5]

Member Function Documentation

◆ Differentiate()

◆ E()

◆ EqualTo()

◆ Evaluate() [1/2]

◆ Evaluate() [2/2]

◆ EvaluatePartial()

◆ Expand()

◆ get_kind()

◆ GetVariables()

◆ is_expanded()

◆ is_polynomial()

◆ Jacobian()

◆ Less()

◆ NaN()

◆ One()

◆ operator++() [1/2]

◆ operator++() [2/2]

◆ operator--() [1/2]

◆ operator--() [2/2]

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ Pi()

◆ Substitute() [1/2]

◆ Substitute() [2/2]

◆ to_string()

◆ Zero()

Friends And Related Function Documentation

◆ abs

◆ acos

◆ asin

◆ atan

◆ atan2

◆ ceil

◆ clamp

◆ cos

◆ cosh

◆ exp

◆ ExpressionAddFactory

◆ ExpressionMulFactory

◆ floor

◆ get_constant_value

◆ hash_append

◆ if_then_else

◆ internal::Gemm

◆ is_abs

◆ is_acos

◆ is_addition

◆ is_asin

◆ is_atan

◆ is_atan2

◆ is_ceil

◆ is_constant [1/2]

◆ is_constant [2/2]

◆ is_cos

◆ is_cosh

◆ is_division

◆ is_exp

◆ is_floor

◆ is_if_then_else

◆ is_log

◆ is_max

◆ is_min

◆ is_multiplication

◆ is_nan

◆ is_pow

◆ is_sin

◆ is_sinh

◆ is_sqrt