LP simplification abstract base class.Instances of classes derived from SPxSimplifier may be loaded to SoPlex in order to simplify LPs before solving them. SoPlex will call simplify() on itself. Generally any SPxLP can be given to a SPxSimplifier for simplify()ing it. The simplification cannot be undone, but given an primal/dual solution for the simplified SPxLP, the simplifier can reconstruct the primal/dual solution of the unsimplified LP. More...

#include <spxsimplifier.h>

Inheritance diagram for SPxSimplifier:

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Public Member Functions
Access / modfication
virtual const char *	getName () const
	get name of simplifier.

virtual Real	timeUsed () const

Simplifying / unsimplifying
virtual Result	simplify (SPxLP &lp, Real eps, Real delta)=0
	simplify SPxLP `lp` with identical primal and dual feasibility tolerance.

virtual Result	simplify (SPxLP &lp, Real eps, Real feastol, Real opttol)=0
	simplify SPxLP `lp` with independent primal and dual feasibility tolerance.

virtual void	unsimplify (const Vector &, const Vector &, const Vector &, const Vector &, const SPxSolver::VarStatus[], const SPxSolver::VarStatus[])
	reconstructs an optimal solution for the unsimplified LP.

virtual bool	isUnsimplified () const
	specifies whether an optimal solution has already been unsimplified.

virtual const Vector &	unsimplifiedPrimal ()=0
	returns a reference to the unsimplified primal solution.

virtual const Vector &	unsimplifiedDual ()=0
	returns a reference to the unsimplified dual solution.

virtual const Vector &	unsimplifiedSlacks ()=0
	returns a reference to the unsimplified slack values.

virtual const Vector &	unsimplifiedRedCost ()=0
	returns a reference to the unsimplified reduced costs.

virtual SPxSolver::VarStatus	getBasisRowStatus (int) const =0
	gets basis status for a single row.

virtual SPxSolver::VarStatus	getBasisColStatus (int) const =0
	gets basis status for a single column.

virtual void	getBasis (SPxSolver::VarStatus[], SPxSolver::VarStatus[]) const =0
	get optimal basis.

virtual Real	getObjoffset () const
	get objective offset.

virtual void	addObjoffset (const Real val)
	add objective offset.

Consistency check
virtual bool	isConsistent () const
	consistency check

Protected Attributes
Protected Data
const char *	m_name
	name of the simplifier

Timer	m_timeUsed
	user time used for simplification

int	m_remRows
	number of removed rows

int	m_remCols
	number of removed columns

int	m_remNzos
	number of removed nonzero coefficients

int	m_chgBnds
	number of changed bounds

int	m_chgLRhs
	number of change right-hand sides

Real	m_objoffset
	objective offset

Types
enum	Result { OKAY = 0, INFEASIBLE = 1, DUAL_INFEASIBLE = 2, UNBOUNDED = 3, VANISHED = 4 }
	Result of the simplification. More...

	SPxSimplifier (const char *p_name)
	constructor

	SPxSimplifier (const SPxSimplifier &old)
	copy constructor

SPxSimplifier &	operator= (const SPxSimplifier &rhs)
	assignment operator

virtual	~SPxSimplifier ()
	destructor.

virtual SPxSimplifier *	clone () const =0
	clone function for polymorphism

Detailed Description

LP simplification abstract base class.

Instances of classes derived from SPxSimplifier may be loaded to SoPlex in order to simplify LPs before solving them. SoPlex will call simplify() on itself. Generally any SPxLP can be given to a SPxSimplifier for simplify()ing it. The simplification cannot be undone, but given an primal/dual solution for the simplified SPxLP, the simplifier can reconstruct the primal/dual solution of the unsimplified LP.

Definition at line 41 of file spxsimplifier.h.

Member Enumeration Documentation

enum Result

Result of the simplification.

Enumerator
OKAY	simplification could be done
INFEASIBLE	primal infeasibility was detected
DUAL_INFEASIBLE	dual infeasibility was detected
UNBOUNDED	primal unboundedness was detected
VANISHED	the problem was so much simplified that it vanished