ibex::Contractor Class Reference
[Contractors]

Contractor base class. More...

#include <IbexContractor.h>

Inheritance diagram for ibex::Contractor:

List of all members.

Public Member Functions
	Contractor (const Contractor &c)
virtual void	contract ()=0
virtual	~Contractor ()
void	contract (const Indicators &p)
void	contract (Space &space, const Indicators &p)
void	contract (Space &space)
bool	contract (Cell &cell, const Indicators &p)
virtual Contractor *	copy () const =0
virtual bool	involves (int ent) const
Cell *	current_cell ()
const Indicators *	current_indic ()
Static Public Member Functions
static Indicators	scope (int x)
static Indicators	impact (int x)
Public Attributes
REAL	contract_floor
Static Public Attributes
static const int	ALL_VARS = -1
static const int	NO_VAR = -2
static const REAL	default_contract_floor = 0.02
Classes
class	Indicators
	Indicators structure for contractors. More...

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Detailed Description

Contractor base class.

Author:

Gilles Chabert

Date:

November 2007

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Constructor & Destructor Documentation

ibex::Contractor::Contractor

(

const Contractor &

c

)

[inline]

Copy constructor.

virtual ibex::Contractor::~Contractor

(

)

[inline, virtual]

Delete this instance.

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Member Function Documentation

virtual void ibex::Contractor::contract

(

)

[pure virtual]

Perform a contraction (in the default space space).

the current_cell() method can be used to get the current cell when this method is called from a paver.

the current_indic() method can be used to get the current indicators when this method is called from a paver, from contract(const Indicators& p) or contract(Space& space,const Indicators& p).

Exceptions:

Must

throw an ibex::UnfeasibilityException is the space box is contracted to the empty set.

Implemented in ibex::BoxNarrow, ibex::Certification, ibex::HC4Revise, ibex::Newton, ibex::Octum, ibex::Precision, ibex::Minimizer, ibex::Propagation, ibex::Sequence, ibex::Shaving, ibex::Slicer, and ibex::UnivNewton.

void ibex::Contractor::contract

(

const Indicators &

p

)

Perform a contraction (in the space space) with indicators p.

See also:

contract().

void ibex::Contractor::contract	(	Space &	space,
		const Indicators &	p
	)

Perform contraction on a space space with indicators p.

Synchronizes (local) space with the (argument) space and calls contract(const Indicators&). The (argument) space is then synchronized back with space, before returning.

Note:

Only the domains of variables should be impacted by this procedure. The domain of any other entity is left unchanged.

See also:

ibex::Cell::space, contract(const Indicators& p).

void ibex::Contractor::contract

(

Space &

space

)

Perform contraction on a space space.

Synchronizes (local) space with the (argument) space and calls contract(). The (argument) space is then synchronized back with space, before returning.

Note:

Only the domains of variables should be impacted by this procedure. The domain of any other entity is left unchanged.

See also:

ibex::Cell::space, contract().

bool ibex::Contractor::contract	(	Cell &	cell,
		const Indicators &	p
	)

Performs contraction on cell with indicators p. This function is called from an ibex::Paver.

When the virtual method contract() is called from this method the current_cell() method can be used to get the current cell. the current_indic() method can be used to get the current indicators.

• Synchronizes (local) space with the space of the cell
• calls contract()
• if contract_floor > 0, perform the following check: if the contraction ratio is greater then synchronize spaces back and return true. Otherwise, restore previous state of the cell and return true.

Ignore all other information of the cell.

Returns:

true when the contraction is effective (see contract_floor). In the case of a non-effective contraction, the space is rollbacked and the function returns false.

See also:

ibex::Cell::space, contract(Space&, const Indicators& p).

virtual Contractor* ibex::Contractor::copy

(

)

const [pure virtual]

Override the interface of the generic operator copy (probably useless).

Implements ibex::Operator.

Implemented in ibex::Box, ibex::BoxNarrow, ibex::Certification, ibex::HC4, ibex::HC4Revise, ibex::Newton, ibex::Octum, ibex::Precision, ibex::Minimizer, ibex::Propagation, ibex::Sequence, ibex::Shaving, ibex::Slicer, and ibex::UnivNewton.

virtual bool ibex::Contractor::involves

(

int

ent

)

const [inline, virtual]

Return true if the entity ent may be impacted by this contractor.

Default implementation: returns true if the entity is in the space.

This function is typically used by ibex::Adjacency to calculate the adjacency list of contractors.

Reimplemented in ibex::BoxNarrow, ibex::HC4Revise, and ibex::Sequence.

Cell* ibex::Contractor::current_cell

(

)

[inline]

Return the current cell (NULL pointer if none).

const Indicators* ibex::Contractor::current_indic

(

)

[inline]

Return the current indicator structure (NULL pointer if none).

static Indicators ibex::Contractor::scope

(

int

x

)

[inline, static]

Create a contractor indicators structure with the scope set to x. (This function is just a kind of macro).

static Indicators ibex::Contractor::impact

(

int

x

)

[inline, static]

Create a contractor indicators structure with the impact set to x. (This function is just a kind of macro).

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Member Data Documentation

const int ibex::Contractor::ALL_VARS = -1 [static]

See also:

Indicators . Its value means "all the variables".

const int ibex::Contractor::NO_VAR = -2 [static]

See also:

Indicators . Its value means "no variable".

REAL ibex::Contractor::contract_floor

Tuning parameter for contraction. A contraction B1->B2 (where B1 is the initial box and B2 the resulting box) is considered to be effective when the maximal ratio between diam(B1[i])/diam(B1[i] \ B2[i])\ > contract_floor. Default value is default_contract_floor. This member can be directly modified.

Note:

if contract_floor is <=0, then contract(Cell&,const Indicators&) will always return true, without checking anything and without making temporary copies of the space box. Setting contract_floor to 0 is then a way to avoid an expensive copy in case of numerous variables.

See also:

INTERVAL_VECTOR::maxratiodelta(const INTERVAL_VECTOR&) const.

const REAL ibex::Contractor::default_contract_floor = 0.02 [static]

Default contraction ceil (used by contract()), set to 0.02.

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

• src/IbexContractor.h
• src/IbexContractor.cpp