A class to express a linear objective. More...

Detailed Description

A class to express a linear objective.

Definition at line 1020 of file linear_solver.h.

#include <linear_solver.h>

Public Member Functions
	MPObjective (const MPObjective &)=delete
	This type is neither copyable nor movable.
MPObjective &	operator= (const MPObjective &)=delete
void	Clear ()
void	SetCoefficient (const MPVariable *var, double coeff)
double	GetCoefficient (const MPVariable *var) const
	--— MPObjective --—
const absl::flat_hash_map< const MPVariable *, double > &	terms () const
void	SetOffset (double value)
	Sets the constant term in the objective.
double	offset () const
	Gets the constant term in the objective.
void	OptimizeLinearExpr (const LinearExpr &linear_expr, bool is_maximization)
void	MaximizeLinearExpr (const LinearExpr &linear_expr)
	Resets the current objective to maximize linear_expr.
void	MinimizeLinearExpr (const LinearExpr &linear_expr)
	Resets the current objective to minimize linear_expr.
void	AddLinearExpr (const LinearExpr &linear_expr)
	Adds linear_expr to the current objective, does not change the direction.
void	SetOptimizationDirection (bool maximize)
	Sets the optimization direction (maximize: true or minimize: false).
void	SetMinimization ()
	Sets the optimization direction to minimize.
void	SetMaximization ()
	Sets the optimization direction to maximize.
bool	maximization () const
	Is the optimization direction set to maximize?
bool	minimization () const
	Is the optimization direction set to minimize?
double	Value () const
double	BestBound () const

Friends
class	MPSolver
class	MPSolverInterface
class	CBCInterface
class	CLPInterface
class	GLPKInterface
class	SCIPInterface
class	SLMInterface
class	GurobiInterface
class	CplexInterface
class	XpressInterface
class	GLOPInterface
class	BopInterface
class	SatInterface
class	PdlpInterface
class	HighsInterface
class	KnapsackInterface

Constructor & Destructor Documentation

◆ MPObjective()

operations_research::MPObjective::MPObjective ( const MPObjective & )

delete

This type is neither copyable nor movable.

Member Function Documentation

◆ AddLinearExpr()

void operations_research::MPObjective::AddLinearExpr ( const LinearExpr & linear_expr )

Adds linear_expr to the current objective, does not change the direction.

Definition at line 242 of file linear_solver.cc.

◆ BestBound()

double operations_research::MPObjective::BestBound ( ) const

Returns the best objective bound.

In case of minimization, it is a lower bound on the objective value of the optimal integer solution. Only available for discrete problems.

Note(user): the best objective bound belongs to the interface for the same reasons as the objective value does.

Definition at line 279 of file linear_solver.cc.

◆ Clear()

void operations_research::MPObjective::Clear ( )

Clears the offset, all variables and coefficients, and the optimization direction.

Definition at line 250 of file linear_solver.cc.

◆ GetCoefficient()

double operations_research::MPObjective::GetCoefficient ( const MPVariable * var ) const

--— MPObjective --—

Gets the coefficient of a given variable in the objective

It returns 0 if the variable does not appear in the objective).

Definition at line 194 of file linear_solver.cc.

◆ maximization()

bool operations_research::MPObjective::maximization ( ) const

Is the optimization direction set to maximize?

Definition at line 268 of file linear_solver.cc.

◆ MaximizeLinearExpr()

void operations_research::MPObjective::MaximizeLinearExpr ( const LinearExpr & linear_expr )

inline

Resets the current objective to maximize linear_expr.

Definition at line 1071 of file linear_solver.h.

◆ minimization()

bool operations_research::MPObjective::minimization ( ) const

Is the optimization direction set to minimize?

Definition at line 270 of file linear_solver.cc.

◆ MinimizeLinearExpr()

void operations_research::MPObjective::MinimizeLinearExpr ( const LinearExpr & linear_expr )

inline

Resets the current objective to minimize linear_expr.

Definition at line 1075 of file linear_solver.h.

◆ offset()

double operations_research::MPObjective::offset ( ) const

inline

Gets the constant term in the objective.

Definition at line 1062 of file linear_solver.h.

◆ operator=()

MPObjective & operations_research::MPObjective::operator= ( const MPObjective & )

delete

◆ OptimizeLinearExpr()

void operations_research::MPObjective::OptimizeLinearExpr	(	const LinearExpr &	linear_expr,
		bool	is_maximization )

Resets the current objective to take the value of linear_expr, and sets the objective direction to maximize if "is_maximize", otherwise minimizes.

Definition at line 230 of file linear_solver.cc.

◆ SetCoefficient()

void operations_research::MPObjective::SetCoefficient	(	const MPVariable *	var,
		double	coeff )

Sets the coefficient of the variable in the objective.

If the variable does not belong to the solver, the function just returns, or crashes in non-opt mode.

See the discussion on MPConstraint::SetCoefficient() for 0 coefficients, the same reasoning applies here.

Definition at line 200 of file linear_solver.cc.

◆ SetMaximization()

void operations_research::MPObjective::SetMaximization ( )

inline

Sets the optimization direction to maximize.

Definition at line 1089 of file linear_solver.h.

◆ SetMinimization()

void operations_research::MPObjective::SetMinimization ( )

inline

Sets the optimization direction to minimize.

Definition at line 1086 of file linear_solver.h.

◆ SetOffset()

void operations_research::MPObjective::SetOffset ( double value )

Sets the constant term in the objective.

Definition at line 215 of file linear_solver.cc.

◆ SetOptimizationDirection()

void operations_research::MPObjective::SetOptimizationDirection ( bool maximize )

Sets the optimization direction (maximize: true or minimize: false).

Note(user): The maximize_ bool would more naturally belong to the MPObjective, but it actually has to be a member of MPSolverInterface, because some implementations (such as GLPK) need that bool for the MPSolverInterface constructor, i.e. at a time when the MPObjective is not constructed yet (MPSolverInterface is always built before MPObjective when a new MPSolver is constructed).

Definition at line 257 of file linear_solver.cc.

◆ terms()

const absl::flat_hash_map< const MPVariable *, double > & operations_research::MPObjective::terms ( ) const

inline

Returns a map from variables to their coefficients in the objective.

If a variable is not present in the map, then its coefficient is zero.

Definition at line 1054 of file linear_solver.h.

◆ Value()

double operations_research::MPObjective::Value ( ) const

Returns the objective value of the best solution found so far.

It is the optimal objective value if the problem has been solved to optimality.

Note: the objective value may be slightly different than what you could compute yourself using MPVariable::solution_value(); please use the –verify_solution flag to gain confidence about the numerical stability of your solution.

Note(user): implementation-wise, the objective value belongs more naturally to the MPSolverInterface, since all of its implementations write to it directly.

Definition at line 272 of file linear_solver.cc.

◆ BopInterface

friend class BopInterface

friend

Definition at line 1130 of file linear_solver.h.

◆ CBCInterface

friend class CBCInterface

friend

Definition at line 1121 of file linear_solver.h.

◆ CLPInterface

friend class CLPInterface

friend

Definition at line 1122 of file linear_solver.h.

◆ CplexInterface

friend class CplexInterface

friend

Definition at line 1127 of file linear_solver.h.

◆ GLOPInterface

friend class GLOPInterface

friend

Definition at line 1129 of file linear_solver.h.

◆ GLPKInterface

friend class GLPKInterface

friend

Definition at line 1123 of file linear_solver.h.

◆ GurobiInterface

friend class GurobiInterface

friend

Definition at line 1126 of file linear_solver.h.

◆ HighsInterface

friend class HighsInterface

friend

Definition at line 1133 of file linear_solver.h.

◆ KnapsackInterface

friend class KnapsackInterface

friend

Definition at line 1134 of file linear_solver.h.

◆ MPSolver

friend class MPSolver

friend

Definition at line 1119 of file linear_solver.h.

◆ MPSolverInterface

friend class MPSolverInterface

friend

Definition at line 1120 of file linear_solver.h.

◆ PdlpInterface

friend class PdlpInterface

friend

Definition at line 1132 of file linear_solver.h.

◆ SatInterface

friend class SatInterface

friend

Definition at line 1131 of file linear_solver.h.

◆ SCIPInterface

friend class SCIPInterface

friend

Definition at line 1124 of file linear_solver.h.

◆ SLMInterface

friend class SLMInterface

friend

Definition at line 1125 of file linear_solver.h.

◆ XpressInterface

friend class XpressInterface

friend

Definition at line 1128 of file linear_solver.h.

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

ortools/linear_solver/linear_solver.h
ortools/linear_solver/linear_solver.cc

Detailed Description

Public Member Functions

Friends

Constructor & Destructor Documentation

◆ MPObjective()

Member Function Documentation

◆ AddLinearExpr()

◆ BestBound()

◆ Clear()

◆ GetCoefficient()

◆ maximization()

◆ MaximizeLinearExpr()

◆ minimization()

◆ MinimizeLinearExpr()

◆ offset()

◆ operator=()

◆ OptimizeLinearExpr()

◆ SetCoefficient()

◆ SetMaximization()

◆ SetMinimization()

◆ SetOffset()

◆ SetOptimizationDirection()

◆ terms()

◆ Value()

Friends And Related Symbol Documentation

◆ BopInterface

◆ CBCInterface

◆ CLPInterface

◆ CplexInterface

◆ GLOPInterface

◆ GLPKInterface

◆ GurobiInterface

◆ HighsInterface

◆ KnapsackInterface

◆ MPSolver

◆ MPSolverInterface

◆ PdlpInterface

◆ SatInterface

◆ SCIPInterface

◆ SLMInterface

◆ XpressInterface