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>

Public Member Functions
void	setOutstream (SPxOut &newOutstream)

virtual void	setTolerances (std::shared_ptr< Tolerances > newTolerances)
	set the _tolerances member variable More...

const std::shared_ptr< Tolerances >	tolerances () const
	get the _tolerances member variable More...

Access / modfication
virtual const char *	getName () const
	get name of simplifier. More...

virtual R	timeUsed () const

Simplifying / unsimplifying
virtual Result	simplify (SPxLPBase< R > &lp, Real remainingTime, bool keepbounds=false, uint32_t seed=0)=0
	simplify SPxLP `lp` More...

virtual void	unsimplify (const VectorBase< R > &, const VectorBase< R > &, const VectorBase< R > &, const VectorBase< R > &, const typename SPxSolverBase< R >::VarStatus[], const typename SPxSolverBase< R >::VarStatus[], bool isOptimal=true)=0
	reconstructs an optimal solution for the unsimplified LP. More...

virtual Result	result () const =0
	returns result status of the simplification More...

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

virtual const VectorBase< R > &	unsimplifiedPrimal ()=0
	returns a reference to the unsimplified primal solution. More...

virtual const VectorBase< R > &	unsimplifiedDual ()=0
	returns a reference to the unsimplified dual solution. More...

virtual const VectorBase< R > &	unsimplifiedSlacks ()=0
	returns a reference to the unsimplified slack values. More...

virtual const VectorBase< R > &	unsimplifiedRedCost ()=0
	returns a reference to the unsimplified reduced costs. More...

virtual SPxSolverBase< R >::VarStatus	getBasisRowStatus (int) const =0
	gets basis status for a single row. More...

virtual SPxSolverBase< R >::VarStatus	getBasisColStatus (int) const =0
	gets basis status for a single column. More...

virtual void	getBasis (typename SPxSolverBase< R >::VarStatus[], typename SPxSolverBase< R >::VarStatus[], const int rowsSize=-1, const int colsSize=-1) const =0
	get optimal basis. More...

virtual R	getObjoffset () const
	get objective offset. More...

virtual void	addObjoffset (const R val)
	add objective offset. More...

virtual void	setMinReduction (const R minRed)
	set minimal reduction threshold to continue simplification More...

Consistency check
virtual bool	isConsistent () const
	consistency check More...

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

Timer *	m_timeUsed
	user time used for simplification More...

Timer::TYPE	m_timerType

int	m_remRows
	number of removed rows More...

int	m_remCols
	number of removed columns More...

int	m_remNzos
	number of removed nonzero coefficients More...

int	m_chgBnds
	number of changed bounds More...

int	m_chgLRhs
	number of change right-hand sides More...

int	m_keptBnds
	number of kept bounds More...

int	m_keptLRhs
	number of kept left- and right-hand sides More...

R	m_objoffset
	objective offset More...

R	m_minReduction
	minimal reduction (sum of removed rows/cols) to continue simplification More...

SPxOut *	spxout
	message handler More...

std::shared_ptr< Tolerances >	_tolerances

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

	SPxSimplifier (const char *p_name, Timer::TYPE ttype=Timer::USER_TIME)
	constructor More...

	SPxSimplifier (const SPxSimplifier &old)
	copy constructor More...

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

virtual	~SPxSimplifier ()
	destructor. More...

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

Detailed Description

template<class R>
class soplex::SPxSimplifier< R >

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 51 of file spxsimplifier.h.

Member Enumeration Documentation

◆ Result

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

Definition at line 92 of file spxsimplifier.h.

Constructor & Destructor Documentation

◆ SPxSimplifier() [1/2]

SPxSimplifier	(	const char *	p_name,
		Timer::TYPE	ttype = `Timer::USER_TIME`
	)

explicit

constructor

Definition at line 106 of file spxsimplifier.h.

◆ SPxSimplifier() [2/2]

SPxSimplifier ( const SPxSimplifier< R > & old )

copy constructor

Definition at line 126 of file spxsimplifier.h.

◆ ~SPxSimplifier()

virtual ~SPxSimplifier ( )

virtual

destructor.

Definition at line 168 of file spxsimplifier.h.

Member Function Documentation

◆ addObjoffset()

virtual void addObjoffset ( const R val )

virtual

add objective offset.

Definition at line 239 of file spxsimplifier.h.

◆ clone()

virtual SPxSimplifier* clone ( ) const

pure virtual

clone function for polymorphism

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::~SPxSimplifier().

◆ getBasis()

virtual void getBasis	(	typename SPxSolverBase< R >::VarStatus	[],
		typename SPxSolverBase< R >::VarStatus	[],
		const int	rowsSize = `-1`,
		const int	colsSize = `-1`
	)		const

pure virtual

get optimal basis.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ getBasisColStatus()

virtual SPxSolverBase<R>::VarStatus getBasisColStatus ( int ) const

pure virtual

gets basis status for a single column.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ getBasisRowStatus()

virtual SPxSolverBase<R>::VarStatus getBasisRowStatus ( int ) const

pure virtual

gets basis status for a single row.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ getName()

virtual const char* getName ( ) const

virtual

get name of simplifier.

Definition at line 182 of file spxsimplifier.h.

◆ getObjoffset()

virtual R getObjoffset ( ) const

virtual

get objective offset.

Definition at line 233 of file spxsimplifier.h.

◆ isConsistent()

virtual bool isConsistent ( ) const

virtual

consistency check

Definition at line 256 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=(), and SPxSimplifier< BP >::SPxSimplifier().

◆ isUnsimplified()

virtual bool isUnsimplified ( ) const

virtual

specifies whether an optimal solution has already been unsimplified.

Reimplemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Definition at line 206 of file spxsimplifier.h.

◆ operator=()

SPxSimplifier& operator= ( const SPxSimplifier< R > & rhs )

assignment operator

Definition at line 144 of file spxsimplifier.h.

Referenced by Presol< BP >::getBasis(), and SPxMainSM< BP >::operator=().

◆ result()

virtual Result result ( ) const

pure virtual

returns result status of the simplification

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::timeUsed().

◆ setMinReduction()

virtual void setMinReduction ( const R minRed )

virtual

set minimal reduction threshold to continue simplification

Definition at line 245 of file spxsimplifier.h.

◆ setOutstream()

void setOutstream ( SPxOut & newOutstream )

Definition at line 262 of file spxsimplifier.h.

◆ setTolerances()

virtual void setTolerances ( std::shared_ptr< Tolerances > newTolerances )

virtual

set the _tolerances member variable

Definition at line 268 of file spxsimplifier.h.

◆ simplify()

virtual Result simplify	(	SPxLPBase< R > &	lp,
		Real	remainingTime,
		bool	keepbounds = `false`,
		uint32_t	seed = `0`
	)

pure virtual

simplify SPxLP lp

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::timeUsed().

◆ timeUsed()

virtual R timeUsed ( ) const

virtual

Definition at line 186 of file spxsimplifier.h.

◆ tolerances()

const std::shared_ptr<Tolerances> tolerances ( ) const

get the _tolerances member variable

Definition at line 273 of file spxsimplifier.h.

Referenced by SPxMainSM< BP >::epsZero(), SPxMainSM< BP >::feastol(), Presol< BP >::getBasis(), and SPxMainSM< BP >::opttol().

◆ unsimplifiedDual()

virtual const VectorBase<R>& unsimplifiedDual ( )

pure virtual

returns a reference to the unsimplified dual solution.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ unsimplifiedPrimal()

virtual const VectorBase<R>& unsimplifiedPrimal ( )

pure virtual

returns a reference to the unsimplified primal solution.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ unsimplifiedRedCost()

virtual const VectorBase<R>& unsimplifiedRedCost ( )

pure virtual

returns a reference to the unsimplified reduced costs.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ unsimplifiedSlacks()

virtual const VectorBase<R>& unsimplifiedSlacks ( )

pure virtual

returns a reference to the unsimplified slack values.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::isUnsimplified().

◆ unsimplify()

virtual void unsimplify	(	const VectorBase< R > &	,
		const VectorBase< R > &	,
		const VectorBase< R > &	,
		const VectorBase< R > &	,
		const typename SPxSolverBase< R >::VarStatus	[],
		const typename SPxSolverBase< R >::VarStatus	[],
		bool	isOptimal = `true`
	)

pure virtual

reconstructs an optimal solution for the unsimplified LP.

Implemented in SPxMainSM< R >, SPxMainSM< BP >, Presol< R >, and Presol< BP >.

Referenced by SPxSimplifier< BP >::timeUsed().

Member Data Documentation

◆ _tolerances

std::shared_ptr<Tolerances> _tolerances

protected

Definition at line 83 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::tolerances().

◆ m_chgBnds

int m_chgBnds

protected

number of changed bounds

Definition at line 69 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_chgLRhs

int m_chgLRhs

protected

number of change right-hand sides

Definition at line 71 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_keptBnds

int m_keptBnds

protected

number of kept bounds

Definition at line 73 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_keptLRhs

int m_keptLRhs

protected

number of kept left- and right-hand sides

Definition at line 75 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_minReduction

R m_minReduction

protected

minimal reduction (sum of removed rows/cols) to continue simplification

Definition at line 79 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_name

const char* m_name

protected

name of the simplifier

Definition at line 58 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::getName(), and SPxSimplifier< BP >::operator=().

◆ m_objoffset

R m_objoffset

protected

objective offset

Definition at line 77 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::getObjoffset(), and SPxSimplifier< BP >::operator=().

◆ m_remCols

int m_remCols

protected

number of removed columns

Definition at line 65 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_remNzos

int m_remNzos

protected

number of removed nonzero coefficients

Definition at line 67 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_remRows

int m_remRows

protected

number of removed rows

Definition at line 63 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_timerType

Timer::TYPE m_timerType

protected

Definition at line 61 of file spxsimplifier.h.

Referenced by SPxSimplifier< BP >::operator=().

◆ m_timeUsed

Timer* m_timeUsed

protected

user time used for simplification

Definition at line 60 of file spxsimplifier.h.

Referenced by Presol< BP >::getBasis(), and SPxSimplifier< BP >::operator=().

◆ spxout

SPxOut* spxout

protected

message handler

tolerances used by the solver

Definition at line 81 of file spxsimplifier.h.

Referenced by Presol< BP >::getBasis(), and SPxSimplifier< BP >::operator=().

SoPlex

Public Member Functions

Protected Attributes

Types

Detailed Description

template<class R> class soplex::SPxSimplifier< R >

Member Enumeration Documentation

◆ Result

Constructor & Destructor Documentation

◆ SPxSimplifier() [1/2]

◆ SPxSimplifier() [2/2]

◆ ~SPxSimplifier()

Member Function Documentation

◆ addObjoffset()

◆ clone()

◆ getBasis()

◆ getBasisColStatus()

◆ getBasisRowStatus()

◆ getName()

◆ getObjoffset()

◆ isConsistent()

◆ isUnsimplified()

◆ operator=()

◆ result()

◆ setMinReduction()

◆ setOutstream()

◆ setTolerances()

◆ simplify()

◆ timeUsed()

◆ tolerances()

◆ unsimplifiedDual()

◆ unsimplifiedPrimal()

◆ unsimplifiedRedCost()

◆ unsimplifiedSlacks()

◆ unsimplify()

Member Data Documentation

◆ _tolerances

◆ m_chgBnds

◆ m_chgLRhs

◆ m_keptBnds

◆ m_keptLRhs

◆ m_minReduction

◆ m_name

◆ m_objoffset

◆ m_remCols

◆ m_remNzos

◆ m_remRows

◆ m_timerType

◆ m_timeUsed

◆ spxout

template<class R>
class soplex::SPxSimplifier< R >