An autodiff expression node. More...

#include </home/runner/work/allwpilib/allwpilib/wpimath/src/main/native/thirdparty/sleipnir/include/sleipnir/autodiff/expression.hpp>

Public Types
using	Scalar = Scalar_
	Scalar type alias.

Public Member Functions
constexpr	Expression ()=default
	Constructs a constant expression with a value of zero.
constexpr	Expression (Scalar value)
	Constructs a nullary expression (an operator with no arguments).
constexpr	Expression (ExpressionPtr< Scalar > lhs)
	Constructs an unary expression (an operator with one argument).
constexpr	Expression (ExpressionPtr< Scalar > lhs, ExpressionPtr< Scalar > rhs)
	Constructs a binary expression (an operator with two arguments).
virtual	~Expression ()=default
constexpr bool	is_constant (Scalar constant) const
	Returns true if the expression is the given constant.
virtual Scalar	value (Scalar lhs, Scalar rhs) const =0
	Either nullary operator with no arguments, unary operator with one argument, or binary operator with two arguments.
virtual ExpressionType	type () const =0
	Returns the type of this expression (constant, linear, quadratic, or nonlinear).
virtual std::string_view	name () const =0
	Returns the name of this expression.
virtual Scalar	grad_l (Scalar lhs, Scalar rhs, Scalar parent_adjoint) const
	Returns ∂/∂l as a Scalar.
virtual Scalar	grad_r (Scalar lhs, Scalar rhs, Scalar parent_adjoint) const
	Returns ∂/∂r as a Scalar.
virtual ExpressionPtr< Scalar >	grad_expr_l (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs, const ExpressionPtr< Scalar > &parent_adjoint) const
	Returns ∂/∂l as an Expression.
virtual ExpressionPtr< Scalar >	grad_expr_r (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs, const ExpressionPtr< Scalar > &parent_adjoint) const
	Returns ∂/∂r as an Expression.

Public Attributes
Scalar	val {0}
	The value of the expression node.
Scalar	adjoint {0}
	The adjoint of the expression node, used during autodiff.
uint32_t	incoming_edges = 0
	Counts incoming edges for this node.
int32_t	col = -1
	This expression's column in a Jacobian, or -1 otherwise.
ExpressionPtr< Scalar >	adjoint_expr
	The adjoint of the expression node, used during gradient expression tree generation.
uint32_t	ref_count = 0
	Reference count for intrusive shared pointer.
std::array< ExpressionPtr< Scalar >, 2 >	args {nullptr, nullptr}
	Expression arguments.

Friends
ExpressionPtr< Scalar >	operator* (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs)
	Expression-Expression multiplication operator.
ExpressionPtr< Scalar >	operator/ (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs)
	Expression-Expression division operator.
ExpressionPtr< Scalar >	operator+ (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs)
	Expression-Expression addition operator.
ExpressionPtr< Scalar >	operator+= (ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs)
	Expression-Expression compound addition operator.
ExpressionPtr< Scalar >	operator- (const ExpressionPtr< Scalar > &lhs, const ExpressionPtr< Scalar > &rhs)
	Expression-Expression subtraction operator.
ExpressionPtr< Scalar >	operator- (const ExpressionPtr< Scalar > &lhs)
	Unary minus operator.
ExpressionPtr< Scalar >	operator+ (const ExpressionPtr< Scalar > &lhs)
	Unary plus operator.

Detailed Description

template<typename Scalar_>
struct slp::detail::Expression< Scalar_ >

An autodiff expression node.

Template Parameters

Scalar Scalar type.

Member Typedef Documentation

◆ Scalar

template<typename Scalar_>

using slp::detail::Expression< Scalar_ >::Scalar = Scalar_

Scalar type alias.

Constructor & Destructor Documentation

◆ Expression() [1/4]

template<typename Scalar_>

slp::detail::Expression< Scalar_ >::Expression ( )

constexprdefault

Constructs a constant expression with a value of zero.

◆ Expression() [2/4]

template<typename Scalar_>

slp::detail::Expression< Scalar_ >::Expression ( Scalar value )

inlineexplicitconstexpr

Constructs a nullary expression (an operator with no arguments).

Parameters

value The expression value.

◆ Expression() [3/4]

template<typename Scalar_>

slp::detail::Expression< Scalar_ >::Expression ( ExpressionPtr< Scalar > lhs )

inlineexplicitconstexpr

Constructs an unary expression (an operator with one argument).

Parameters

lhs	Unary operator's operand.

◆ Expression() [4/4]

template<typename Scalar_>

slp::detail::Expression< Scalar_ >::Expression	(	ExpressionPtr< Scalar >	lhs,
		ExpressionPtr< Scalar >	rhs )

inlineconstexpr

Constructs a binary expression (an operator with two arguments).

Parameters

lhs	Binary operator's left operand.
rhs	Binary operator's right operand.

◆ ~Expression()

template<typename Scalar_>

virtual slp::detail::Expression< Scalar_ >::~Expression ( )

virtualdefault

Member Function Documentation

◆ grad_expr_l()

template<typename Scalar_>

virtual ExpressionPtr< Scalar > slp::detail::Expression< Scalar_ >::grad_expr_l	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs,
		const ExpressionPtr< Scalar > &	parent_adjoint ) const

inlinevirtual

Returns ∂/∂l as an Expression.

Parameters

lhs	Left argument to binary operator.
rhs	Right argument to binary operator.
parent_adjoint	Adjoint of parent expression.

Returns: ∂/∂l as an Expression.

◆ grad_expr_r()

template<typename Scalar_>

virtual ExpressionPtr< Scalar > slp::detail::Expression< Scalar_ >::grad_expr_r	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs,
		const ExpressionPtr< Scalar > &	parent_adjoint ) const

inlinevirtual

Returns ∂/∂r as an Expression.

Parameters

lhs	Left argument to binary operator.
rhs	Right argument to binary operator.
parent_adjoint	Adjoint of parent expression.

Returns: ∂/∂r as an Expression.

Reimplemented in slp::detail::Atan2Expression< Scalar >, slp::detail::BinaryMinusExpression< Scalar, T >, slp::detail::BinaryPlusExpression< Scalar, T >, slp::detail::DivExpression< Scalar, T >, slp::detail::HypotExpression< Scalar >, slp::detail::MultExpression< Scalar, T >, and slp::detail::PowExpression< Scalar, T >.

◆ grad_l()

template<typename Scalar_>

virtual Scalar slp::detail::Expression< Scalar_ >::grad_l	(	Scalar	lhs,
		Scalar	rhs,
		Scalar	parent_adjoint ) const

inlinevirtual

Returns ∂/∂l as a Scalar.

Parameters

lhs	Left argument to binary operator.
rhs	Right argument to binary operator.
parent_adjoint	Adjoint of parent expression.

Returns: ∂/∂l as a Scalar.

◆ grad_r()

template<typename Scalar_>

virtual Scalar slp::detail::Expression< Scalar_ >::grad_r	(	Scalar	lhs,
		Scalar	rhs,
		Scalar	parent_adjoint ) const

inlinevirtual

Returns ∂/∂r as a Scalar.

Parameters

lhs	Left argument to binary operator.
rhs	Right argument to binary operator.
parent_adjoint	Adjoint of parent expression.

Returns: ∂/∂r as a Scalar.

Reimplemented in slp::detail::Atan2Expression< Scalar >, slp::detail::BinaryMinusExpression< Scalar, T >, slp::detail::BinaryPlusExpression< Scalar, T >, slp::detail::DivExpression< Scalar, T >, slp::detail::HypotExpression< Scalar >, slp::detail::MultExpression< Scalar, T >, and slp::detail::PowExpression< Scalar, T >.

◆ is_constant()

template<typename Scalar_>

bool slp::detail::Expression< Scalar_ >::is_constant ( Scalar constant ) const

inlineconstexpr

Returns true if the expression is the given constant.

Parameters

constant The constant.

Returns: True if the expression is the given constant.

◆ name()

template<typename Scalar_>

virtual std::string_view slp::detail::Expression< Scalar_ >::name ( ) const

pure virtual

Returns the name of this expression.

Returns: The name of this expression.

◆ type()

template<typename Scalar_>

virtual ExpressionType slp::detail::Expression< Scalar_ >::type ( ) const

pure virtual

Returns the type of this expression (constant, linear, quadratic, or nonlinear).

Returns: The type of this expression.

◆ value()

template<typename Scalar_>

virtual Scalar slp::detail::Expression< Scalar_ >::value	(	Scalar	lhs,
		Scalar	rhs ) const

pure virtual

Either nullary operator with no arguments, unary operator with one argument, or binary operator with two arguments.

This operator is used to update the node's value.

Parameters

lhs	Left argument to binary operator.
rhs	Right argument to binary operator.

Returns: The node's value.

◆ operator*

template<typename Scalar_>

ExpressionPtr< Scalar > operator*	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs )

friend

Expression-Expression multiplication operator.

Parameters

lhs	Operator left-hand side.
rhs	Operator right-hand side.

◆ operator+ [1/2]

template<typename Scalar_>

ExpressionPtr< Scalar > operator+ ( const ExpressionPtr< Scalar > & lhs )

friend

Unary plus operator.

Parameters

lhs	Operand of unary plus.

◆ operator+ [2/2]

template<typename Scalar_>

ExpressionPtr< Scalar > operator+	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs )

friend

Expression-Expression addition operator.

Parameters

lhs	Operator left-hand side.
rhs	Operator right-hand side.

◆ operator+=

template<typename Scalar_>

ExpressionPtr< Scalar > operator+=	(	ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs )

friend

Expression-Expression compound addition operator.

Parameters

lhs	Operator left-hand side.
rhs	Operator right-hand side.

◆ operator- [1/2]

template<typename Scalar_>

ExpressionPtr< Scalar > operator- ( const ExpressionPtr< Scalar > & lhs )

friend

Unary minus operator.

Parameters

lhs	Operand of unary minus.

◆ operator- [2/2]

template<typename Scalar_>

ExpressionPtr< Scalar > operator-	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs )

friend

Expression-Expression subtraction operator.

Parameters

lhs	Operator left-hand side.
rhs	Operator right-hand side.

◆ operator/

template<typename Scalar_>

ExpressionPtr< Scalar > operator/	(	const ExpressionPtr< Scalar > &	lhs,
		const ExpressionPtr< Scalar > &	rhs )

friend

Expression-Expression division operator.

Parameters

lhs	Operator left-hand side.
rhs	Operator right-hand side.

Member Data Documentation

◆ adjoint

template<typename Scalar_>

Scalar slp::detail::Expression< Scalar_ >::adjoint {0}

The adjoint of the expression node, used during autodiff.

◆ adjoint_expr

template<typename Scalar_>

ExpressionPtr<Scalar> slp::detail::Expression< Scalar_ >::adjoint_expr

The adjoint of the expression node, used during gradient expression tree generation.

◆ args

template<typename Scalar_>

std::array<ExpressionPtr<Scalar>, 2> slp::detail::Expression< Scalar_ >::args {nullptr, nullptr}

Expression arguments.

◆ col

template<typename Scalar_>

int32_t slp::detail::Expression< Scalar_ >::col = -1

This expression's column in a Jacobian, or -1 otherwise.

◆ incoming_edges

template<typename Scalar_>

uint32_t slp::detail::Expression< Scalar_ >::incoming_edges = 0

Counts incoming edges for this node.

◆ ref_count

template<typename Scalar_>

uint32_t slp::detail::Expression< Scalar_ >::ref_count = 0

Reference count for intrusive shared pointer.

◆ val

template<typename Scalar_>

Scalar slp::detail::Expression< Scalar_ >::val {0}

The value of the expression node.

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

/home/runner/work/allwpilib/allwpilib/wpimath/src/main/native/thirdparty/sleipnir/include/sleipnir/autodiff/expression.hpp

Public Types

Public Member Functions

Public Attributes

Friends

Detailed Description

Member Typedef Documentation

◆ Scalar

Constructor & Destructor Documentation

◆ Expression() [1/4]

◆ Expression() [2/4]

◆ Expression() [3/4]

◆ Expression() [4/4]

◆ ~Expression()

Member Function Documentation

◆ grad_expr_l()

◆ grad_expr_r()

◆ grad_l()

◆ grad_r()

◆ is_constant()

◆ name()

◆ type()

◆ value()

Friends And Related Symbol Documentation

◆ operator*

◆ operator+ [1/2]

◆ operator+ [2/2]

◆ operator+=

◆ operator- [1/2]

◆ operator- [2/2]

◆ operator/

Member Data Documentation

◆ adjoint

◆ adjoint_expr

◆ args

◆ col

◆ incoming_edges

◆ ref_count

◆ val