Minimum tape interface for a working reverse tape implementation. More...

#include <reverseTapeInterface.hpp>

Inheritance diagram for codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >:

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Public Types
using	Gradient = T_Gradient
	See ReverseTapeInterface.

using	Identifier = T_Identifier
	See ReverseTapeInterface.

using	PassiveReal = RealTraits::PassiveReal<Real>
	Basic computation type.

using	Real = T_Real
	See ReverseTapeInterface.

Public Types inherited from codi::InternalStatementRecordingTapeInterface< T_Identifier >
using	Identifier = T_Identifier
	See InternalStatementRecordingTapeInterface.

Public Types inherited from codi::GradientAccessTapeInterface< T_Gradient, T_Identifier >
using	Gradient = T_Gradient
	See GradientAccessTapeInterface.

using	Identifier = T_Identifier
	See GradientAccessTapeInterface.

Public Member Functions
Recording
template<typename Lhs, typename Tape>
void	registerInput (LhsExpressionInterface< Real, Gradient, Tape, Lhs > &value)

template<typename Lhs, typename Tape>
void	registerOutput (LhsExpressionInterface< Real, Gradient, Tape, Lhs > &value)

void	setActive ()
	Start/continue recording of statements.

void	setPassive ()
	Stop/interrupt recording of statements.

bool	isActive () const
	Check if the tape is recording.

Reversal
void	evaluate (AdjointsManagement adjointsManagement=AdjointsManagement::Automatic)
	Perform a full reverse evaluation of the tape.

Reset
void	clearAdjoints (AdjointsManagement adjointsManagement=AdjointsManagement::Automatic)
	Clear all adjoint values, that is, set them to zero.

void	reset (bool resetAdjoints=true, AdjointsManagement adjointsManagement=AdjointsManagement::Automatic)
	Reset the tape to the initial state for a fresh recording.

Tape information
template<typename Stream = std::ostream>
void	printStatistics (Stream &out=std::cout) const
	Default formatting of TapeValues.

template<typename Stream = std::ostream>
void	printTableHeader (Stream &out=std::cout) const
	Table header output of TapeValues.

template<typename Stream = std::ostream>
void	printTableRow (Stream &out=std::cout) const
	Table row output of TapeValues.

TapeValues	getTapeValues () const
	Get current tape values.

template<typename Real>
void	initIdentifier (Real &value, Identifier &identifier)

template<typename Real>
void	destroyIdentifier (Real &value, Identifier &identifier)
	Has to be called for each identifier, before it is deallocated.

template<typename Lhs, typename Rhs>
void	store (Lhs &lhs, Rhs const &rhs)
	Has to be called by an AD variable every time it is assigned.

Public Member Functions inherited from codi::GradientAccessTapeInterface< T_Gradient, T_Identifier >
void	setGradient (Identifier const &identifier, Gradient const &gradient, AdjointsManagement adjointsManagement=AdjointsManagement::Automatic)
	Set the gradient.

Gradient const &	getGradient (Identifier const &identifier, AdjointsManagement adjointsManagement=AdjointsManagement::Automatic) const
	Set the gradient.

Gradient &	gradient (Identifier const &identifier, AdjointsManagement adjointsManagement=AdjointsManagement::Automatic)
	Reference access to gradient.

Gradient const &	gradient (Identifier const &identifier, AdjointsManagement adjointsManagement=AdjointsManagement::Automatic) const
	Constant reference access to gradient.

Additional Inherited Members
static bool constexpr	AllowJacobianOptimization
	If certain operations can be hidden from the tape.

Detailed Description

template<typename T_Real, typename T_Gradient, typename T_Identifier>
struct codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >

Minimum tape interface for a working reverse tape implementation.

See Tape Interface Design for a general overview of the tape interface design in CoDiPack.

For an example on how to uses this interface to perform an AD reverse mode recording and evaluation of a program, please see tutorials Tutorial 2 - Reverse mode AD and Tutorial 5 - Repeated tape recordings).

Implementation hints: A tape should only record information if it is active, that is, everything between a call to setActive() and setPassive(). A call to setActive() does not reset the tape in CoDiPack. A reset can only be performed by a call to reset(). Hence, the user may skip unnecessarys parts of the recording by setting the tape passive for these regions.

Here is an example for using a tape (documentation/examples/reverseModeAD.cpp):

  using Real = codi::RealReverse;
  using Tape = typename Real::Tape;
 
  Tape& tape = Real::getTape();
 
  // Recording
  Real x = 10.0;
 
  tape.setActive();
  tape.registerInput(x);
 
  Real y = 42.0 * x * x;
 
  tape.registerOutput(y);
  tape.setPassive();
 
  // Reverse evaluation
  y.setGradient(1.0);
  tape.evaluate();
 
  std::cout << "Gradient of dy/dx: " << x.getGradient() << std::endl;

Template Parameters

T_Real	The computation type of a tape, usually chosen as ActiveType::Real.
T_Gradient	The gradient type of a tape, usually chosen as ActiveType::Gradient.
T_Identifier	The adjoint/tangent identification of a tape, usually chosen as ActiveType::Identifier.

Member Function Documentation

◆ clearAdjoints()

template<typename T_Real, typename T_Gradient, typename T_Identifier>

void codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >::clearAdjoints ( AdjointsManagement adjointsManagement = AdjointsManagement::Automatic )

Clear all adjoint values, that is, set them to zero.

Automatic adjoints management involves locking, see AdjointsManagement for details.

◆ evaluate()

template<typename T_Real, typename T_Gradient, typename T_Identifier>

void codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >::evaluate ( AdjointsManagement adjointsManagement = AdjointsManagement::Automatic )

Perform a full reverse evaluation of the tape.

Automatic adjoints management involves bounds checking, resizing, and locking, see AdjointsManagement for details.

◆ registerInput()

template<typename T_Real, typename T_Gradient, typename T_Identifier>

template<typename Lhs, typename Tape>

void codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >::registerInput ( LhsExpressionInterface< Real, Gradient, Tape, Lhs > & value )

Mark a value as input (independent) and make it active.

Template Parameters

Lhs	Class that implements the LhsExpressionInterface. See also LhsExpressionInterface.
Tape	Tape implementation used in the LhsExpressionInterface. See also LhsExpressionInterface.

◆ registerOutput()

template<typename T_Real, typename T_Gradient, typename T_Identifier>

template<typename Lhs, typename Tape>

void codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >::registerOutput ( LhsExpressionInterface< Real, Gradient, Tape, Lhs > & value )

Mark a value as output (dependent).

Template Parameters

Lhs	Class that implements the LhsExpressionInterface. See also LhsExpressionInterface.
Tape	Tape implementation used in the LhsExpressionInterface. See also LhsExpressionInterface.

◆ reset()

template<typename T_Real, typename T_Gradient, typename T_Identifier>

void codi::ReverseTapeInterface< T_Real, T_Gradient, T_Identifier >::reset	(	bool	resetAdjoints = true,
		AdjointsManagement	adjointsManagement = AdjointsManagement::Automatic )

Reset the tape to the initial state for a fresh recording.

See Tutorial 5 - Repeated tape recordings for remarks on repeated tape recording in CoDiPack.

Automatic adjoints management involves locking, see AdjointsManagement for details.

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

include/codi/tapes/interfaces/reverseTapeInterface.hpp

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ clearAdjoints()

◆ evaluate()

◆ registerInput()

◆ registerOutput()

◆ reset()