SbbSimpleInteger Class Reference

Define a single integer class. More...

#include <SbbBranchActual.hpp>

Inheritance diagram for SbbSimpleInteger:

List of all members.

Public Member Functions
	SbbSimpleInteger ()
	SbbSimpleInteger (SbbModel *model, int sequence, int iColumn)
	SbbSimpleInteger (const SbbSimpleInteger &)
virtual SbbObject *	clone () const
	Clone.
SbbSimpleInteger &	operator= (const SbbSimpleInteger &rhs)
virtual double	infeasibility (int &preferredWay, double &otherWay) const
	Infeasibility - large is 0.5.
virtual void	feasibleRegion ()
virtual SbbBranchingObject *	createBranch (int way) const
	Creates a branching object.
virtual SbbBranchingObject *	preferredNewFeasible () const
	Given a valid solution (with reduced costs, etc.), return a branching object which would give a new feasible point in the good direction.
virtual SbbBranchingObject *	notPreferredNewFeasible () const
	Given a valid solution (with reduced costs, etc.), return a branching object which would give a new feasible point in a bad direction.
virtual void	resetBounds ()
int	sequence () const
	Sequence number.
int	modelSequence () const
	Model column number.
double	originalLowerBound () const
	Original bounds.
double	originalUpperBound () const
Private Attributes
int	sequence_
	data Sequence
int	columnNumber_
	Column number in model.
double	originalLower_
	Original lower bound.
double	originalUpper_
	Original upper bound.

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Detailed Description

Define a single integer class.

Definition at line 89 of file SbbBranchActual.hpp.

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Constructor & Destructor Documentation

SbbSimpleInteger::SbbSimpleInteger (   )

Default Constructor Equivalent to an unspecified binary variable. Definition at line 300 of file SbbBranchActual.cpp. Referenced by clone(). : SbbObject(), sequence_(-1), columnNumber_(-1), originalLower_(0.0), originalUpper_(1.0) { }

SbbSimpleInteger::SbbSimpleInteger (  SbbModel *  model, int  sequence, int  iColumn )

Useful constructor Loads actual upper & lower bounds for the specified variable. Definition at line 313 of file SbbBranchActual.cpp. References columnNumber_, OsiSolverInterface::getColLower(), OsiSolverInterface::getColUpper(), originalLower_, originalUpper_, sequence_, and SbbModel::solver(). : SbbObject(model) { sequence_ = sequence ; columnNumber_ = iColumn ; originalLower_ = model_->solver()->getColLower()[columnNumber_] ; originalUpper_ = model_->solver()->getColUpper()[columnNumber_] ; }

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Member Function Documentation

void SbbSimpleInteger::feasibleRegion (   )  [virtual]

Set bounds to contain the current solution. More precisely, for the variable associated with this object, take the value given in the current solution, force it within the current bounds if required, then set the bounds to fix the variable at the integer nearest the solution value. Implements SbbObject. Definition at line 390 of file SbbBranchActual.cpp. References columnNumber_, SbbModel::currentSolution(), OsiSolverInterface::getColLower(), OsiSolverInterface::getColUpper(), SbbModel::getDblParam(), OsiSolverInterface::setColLower(), OsiSolverInterface::setColUpper(), and SbbModel::solver(). { OsiSolverInterface * solver = model_->solver(); const double * lower = solver->getColLower(); const double * upper = solver->getColUpper(); const double * solution = model_->currentSolution(); double value = solution[columnNumber_]; value = max(value, lower[columnNumber_]); value = min(value, upper[columnNumber_]); double nearest = floor(value+0.5); double integerTolerance = model_->getDblParam(SbbModel::SbbIntegerTolerance); // Scaling may have moved it a bit assert (fabs(value-nearest)<=100.0*integerTolerance); solver->setColLower(columnNumber_,nearest); solver->setColUpper(columnNumber_,nearest); }

SbbBranchingObject * SbbSimpleInteger::notPreferredNewFeasible (   )  const [virtual]

Given a valid solution (with reduced costs, etc.), return a branching object which would give a new feasible point in a bad direction. As for preferredNewFeasible(), but the preferred branching object will force movement in a direction that degrades the objective. Reimplemented from SbbObject. Definition at line 470 of file SbbBranchActual.cpp. References columnNumber_, SbbModel::currentSolution(), SbbModel::getDblParam(), OsiSolverInterface::getObjSense(), OsiSolverInterface::getReducedCost(), originalLower_, originalUpper_, sequence_, and SbbModel::solver(). { OsiSolverInterface * solver = model_->solver(); double value = model_->currentSolution()[columnNumber_]; double nearest = floor(value+0.5); double integerTolerance = model_->getDblParam(SbbModel::SbbIntegerTolerance); assert (fabs(value-nearest)<=integerTolerance); double dj = solver->getObjSense()*solver->getReducedCost()[columnNumber_]; SbbIntegerBranchingObject * object = NULL; if (dj<=0.0) { // can we go down if (nearest>originalLower_+0.5) { // yes object = new SbbIntegerBranchingObject(model_,sequence_,-1, nearest-1.0,nearest-1.0); } } else { // can we go up if (nearest<originalUpper_-0.5) { // yes object = new SbbIntegerBranchingObject(model_,sequence_,-1, nearest+1.0,nearest+1.0); } } return object; }

SbbBranchingObject * SbbSimpleInteger::preferredNewFeasible (   )  const [virtual]

Given a valid solution (with reduced costs, etc.), return a branching object which would give a new feasible point in the good direction. The preferred branching object will force the variable to be +/-1 from its current value, depending on the reduced cost and objective sense. If movement in the direction which improves the objective is impossible due to bounds on the variable, the branching object will move in the other direction. If no movement is possible, the method returns NULL. Only the bounds on this variable are considered when determining if the new point is feasible. Reimplemented from SbbObject. Definition at line 435 of file SbbBranchActual.cpp. References columnNumber_, SbbModel::currentSolution(), SbbModel::getDblParam(), OsiSolverInterface::getObjSense(), OsiSolverInterface::getReducedCost(), originalLower_, originalUpper_, sequence_, and SbbModel::solver(). { OsiSolverInterface * solver = model_->solver(); double value = model_->currentSolution()[columnNumber_]; double nearest = floor(value+0.5); double integerTolerance = model_->getDblParam(SbbModel::SbbIntegerTolerance); assert (fabs(value-nearest)<=integerTolerance); double dj = solver->getObjSense()*solver->getReducedCost()[columnNumber_]; SbbIntegerBranchingObject * object = NULL; if (dj>=0.0) { // can we go down if (nearest>originalLower_+0.5) { // yes object = new SbbIntegerBranchingObject(model_,sequence_,-1, nearest-1.0,nearest-1.0); } } else { // can we go up if (nearest<originalUpper_-0.5) { // yes object = new SbbIntegerBranchingObject(model_,sequence_,-1, nearest+1.0,nearest+1.0); } } return object; }

void SbbSimpleInteger::resetBounds (   )  [virtual]

Reset original upper and lower bound values from the solver. Handy for updating bounds held in this object after bounds held in the solver have been tightened. Reimplemented from SbbObject. Definition at line 504 of file SbbBranchActual.cpp. References columnNumber_, OsiSolverInterface::getColLower(), OsiSolverInterface::getColUpper(), originalLower_, originalUpper_, and SbbModel::solver(). { originalLower_ = model_->solver()->getColLower()[columnNumber_]; originalUpper_ = model_->solver()->getColUpper()[columnNumber_]; }

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

• SbbBranchActual.hpp
• SbbBranchActual.cpp

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