DoubleLinearExpr

Detailed Description

A dedicated container for linear expressions with double coefficients.

This is currently only usable to define a floating point objective.

Usage:

CpModelBuilder cp_model;
IntVar x = model.NewIntVar({0, 10}).WithName("x");
IntVar y = model.NewIntVar({0, 10}).WithName("y");
BoolVar b = model.NewBoolVar().WithName("b");
BoolVar c = model.NewBoolVar().WithName("c");
DoubleLinearExpr e1(x);  // e1 = x.
// e2 = x + y + 5
DoubleLinearExpr e2 = DoubleLinearExpr::Sum({x, y}).AddConstant(5.0);
// e3 = 2 * x - y
DoubleLinearExpr e3 = DoubleLinearExpr::WeightedSum({x, y}, {2, -1});
DoubleLinearExpr e4(b);  // e4 = b.
DoubleLinearExpr e5(b.Not());  // e5 = 1 - b.
// If passing a std::vector<BoolVar>, a specialized method must be called.
std::vector<BoolVar> bools = {b, Not(c)};
DoubleLinearExpr e6 = DoubleLinearExpr::Sum(bools);  // e6 = b + 1 - c;
// e7 = -3.0 * b + 1.5 - 1.5 * c;
DoubleLinearExpr e7 = DoubleLinearExpr::WeightedSum(bools, {-3.0, 1.5});

This can be used in the objective definition.

// Minimize 3.4 * y + 5.2
cp_model.Minimize(DoubleLinearExpr::Term(y, 3.4).AddConstant(5.2));

Definition at line 345 of file cp_model.h.

Public Member Functions
	DoubleLinearExpr ()
	DoubleLinearExpr (BoolVar var)
	Constructs a linear expression from a Boolean variable. More...
	DoubleLinearExpr (IntVar var)
	Constructs a linear expression from an integer variable. More...
	DoubleLinearExpr (double constant)
	Constructs a constant linear expression. More...
DoubleLinearExpr &	operator+= (double value)
	Adds a constant value to the linear expression. More...
DoubleLinearExpr &	operator+= (IntVar var)
	Adds a single integer variable to the linear expression. More...
DoubleLinearExpr &	operator+= (BoolVar var)
DoubleLinearExpr &	operator+= (const DoubleLinearExpr &expr)
	Adds another linear expression to the linear expression. More...
DoubleLinearExpr &	AddTerm (IntVar var, double coeff)
	Adds a term (var * coeff) to the linear expression. More...
DoubleLinearExpr &	AddTerm (BoolVar var, double coeff)
DoubleLinearExpr &	AddExpression (const LinearExpr &exprs, double coeff=1.0)
	Adds a linear expression to the double linear expression. More...
DoubleLinearExpr &	operator-= (double value)
	Adds a constant value to the linear expression. More...
DoubleLinearExpr &	operator-= (IntVar var)
	Adds a single integer variable to the linear expression. More...
DoubleLinearExpr &	operator-= (const DoubleLinearExpr &expr)
	Adds another linear expression to the linear expression. More...
DoubleLinearExpr &	operator*= (double coeff)
	Multiply the linear expression by a constant. More...
const std::vector< int > &	variables () const
	Returns the vector of variable indices. More...
const std::vector< double > &	coefficients () const
	Returns the vector of coefficients. More...
const bool	IsConstant () const
double	constant () const
	Returns the constant term. More...
std::string	DebugString (const CpModelProto *proto=nullptr) const
	Debug string. See the documentation for LinearExpr::DebugString(). More...

Static Public Member Functions
static DoubleLinearExpr	Sum (absl::Span< const IntVar > vars)
	Constructs the sum of a list of variables. More...
static DoubleLinearExpr	Sum (absl::Span< const BoolVar > vars)
	Constructs the sum of a list of Boolean variables. More...
static DoubleLinearExpr	WeightedSum (absl::Span< const IntVar > vars, absl::Span< const double > coeffs)
	Constructs the scalar product of variables and coefficients. More...
static DoubleLinearExpr	WeightedSum (absl::Span< const BoolVar > vars, absl::Span< const double > coeffs)
	Constructs the scalar product of Boolean variables and coefficients. More...

Constructor & Destructor Documentation

DoubleLinearExpr() [1/4]

DoubleLinearExpr

(

)

DoubleLinearExpr() [2/4]

DoubleLinearExpr ( BoolVar  var )

explicit

Constructs a linear expression from a Boolean variable.

It deals with logical negation correctly.

DoubleLinearExpr() [3/4]

DoubleLinearExpr ( IntVar  var )

explicit

Constructs a linear expression from an integer variable.

DoubleLinearExpr() [4/4]

DoubleLinearExpr ( double  constant )

explicit

Constructs a constant linear expression.

Member Function Documentation

AddExpression()

DoubleLinearExpr& AddExpression	(	const LinearExpr &	exprs,
		double	coeff = 1.0
	)

Adds a linear expression to the double linear expression.

AddTerm() [1/2]

DoubleLinearExpr& AddTerm	(	BoolVar	var,
		double	coeff
	)

AddTerm() [2/2]

DoubleLinearExpr& AddTerm	(	IntVar	var,
		double	coeff
	)

Adds a term (var * coeff) to the linear expression.

coefficients()

const std::vector<double>& coefficients ( ) const

inline

Returns the vector of coefficients.

Definition at line 406 of file cp_model.h.

constant()

double constant ( ) const

inline

Returns the constant term.

Definition at line 412 of file cp_model.h.

DebugString()

std::string DebugString

(

const CpModelProto *

proto = nullptr

)

const

Debug string. See the documentation for LinearExpr::DebugString().

IsConstant()

const bool IsConstant ( ) const

inline

Definition at line 409 of file cp_model.h.

operator*=()

DoubleLinearExpr& operator*=

(

double

coeff

)

Multiply the linear expression by a constant.

operator+=() [1/4]

DoubleLinearExpr& operator+=

(

BoolVar

var

)

operator+=() [2/4]

DoubleLinearExpr& operator+=

(

const DoubleLinearExpr &

expr

)

Adds another linear expression to the linear expression.

operator+=() [3/4]

DoubleLinearExpr& operator+=

(

double

value

)

Adds a constant value to the linear expression.

operator+=() [4/4]

DoubleLinearExpr& operator+=

(

IntVar

var

)

Adds a single integer variable to the linear expression.

operator-=() [1/3]

DoubleLinearExpr& operator-=

(

const DoubleLinearExpr &

expr

)

Adds another linear expression to the linear expression.

operator-=() [2/3]

DoubleLinearExpr& operator-=

(

double

value

)

Adds a constant value to the linear expression.

operator-=() [3/3]

DoubleLinearExpr& operator-=

(

IntVar

var

)

Adds a single integer variable to the linear expression.

Sum() [1/2]

static DoubleLinearExpr Sum ( absl::Span< const BoolVar >  vars )

static

Constructs the sum of a list of Boolean variables.

Sum() [2/2]

static DoubleLinearExpr Sum ( absl::Span< const IntVar >  vars )

static

Constructs the sum of a list of variables.

variables()

const std::vector<int>& variables ( ) const

inline

Returns the vector of variable indices.

Definition at line 403 of file cp_model.h.

WeightedSum() [1/2]

static DoubleLinearExpr WeightedSum ( absl::Span< const BoolVar >  vars, absl::Span< const double >  coeffs  )

static

Constructs the scalar product of Boolean variables and coefficients.

WeightedSum() [2/2]

static DoubleLinearExpr WeightedSum ( absl::Span< const IntVar >  vars, absl::Span< const double >  coeffs  )

static

Constructs the scalar product of variables and coefficients.

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

• cp_model.h