SPxDefaultRT Class Reference

Textbook ratio test for SoPlex.Class SPxDefaultRT provides an implementation of the textbook ratio test as a derived class of SPxRatioTester. This class is not intended for reliably solving LPs (even though it does the job for ``numerically simple'' LPs). Instead, it should serve as a demonstration of how to write ratio tester classes. More...

#include <spxdefaultrt.h>

Inheritance diagram for SPxDefaultRT:

Public Member Functions
Construction / destruction
	SPxDefaultRT ()
	default constructor
	SPxDefaultRT (const SPxDefaultRT &old)
	copy constructor
SPxDefaultRT &	operator= (const SPxDefaultRT &rhs)
	assignment operator
virtual	~SPxDefaultRT ()
	destructor
virtual SPxRatioTester *	clone () const
	clone function for polymorphism
Select enter/leave
virtual int	selectLeave (Real &val, Real)
virtual SPxId	selectEnter (Real &val, int)
Public Member Functions inherited from SPxRatioTester
virtual const char *	getName () const
	get name of ratio tester.
virtual void	load (SPxSolver *p_solver)
	loads LP.
virtual void	clear ()
	unloads LP.
virtual SPxSolver *	solver () const
	returns loaded LP solver.
virtual void	setDelta (Real newDelta)
	set allowed bound violation
virtual Real	getDelta ()
	get allowed bound violation
virtual void	setType (SPxSolver::Type)
	sets Simplex type.
	SPxRatioTester (const char *name)
	default constructor
	SPxRatioTester (const SPxRatioTester &old)
	copy constructor
SPxRatioTester &	operator= (const SPxRatioTester &rhs)
	assignment operator
virtual	~SPxRatioTester ()
	destructor.

Additional Inherited Members
Protected Attributes inherited from SPxRatioTester
SPxSolver *	thesolver
	the solver
const char *	m_name
	name of the ratio tester
SPxSolver::Type	m_type
	internal storage of type
Real	delta
	allowed bound violation

Detailed Description

Textbook ratio test for SoPlex.

Class SPxDefaultRT provides an implementation of the textbook ratio test as a derived class of SPxRatioTester. This class is not intended for reliably solving LPs (even though it does the job for ``numerically simple'' LPs). Instead, it should serve as a demonstration of how to write ratio tester classes.

See SPxRatioTester for a class documentation.

Definition at line 42 of file spxdefaultrt.h.

Constructor & Destructor Documentation

SPxDefaultRT

(

)

default constructor

Definition at line 50 of file spxdefaultrt.h.

Referenced by SPxDefaultRT::clone().

SPxDefaultRT

(

const SPxDefaultRT &

old

)

copy constructor

Definition at line 54 of file spxdefaultrt.h.

virtual ~SPxDefaultRT ( )

virtual

destructor

Definition at line 68 of file spxdefaultrt.h.

Member Function Documentation

virtual SPxRatioTester* clone ( ) const

virtual

clone function for polymorphism

Implements SPxRatioTester.

Definition at line 71 of file spxdefaultrt.h.

References SPxDefaultRT::SPxDefaultRT().

SPxDefaultRT& operator=

(

const SPxDefaultRT &

rhs

)

assignment operator

Definition at line 58 of file spxdefaultrt.h.

References SPxRatioTester::operator=().

SPxId selectEnter ( Real &  max, int    )

virtual

Here comes the ratio test. It is assumed that theCoPvec.delta() and theCoPvec.idx() have been setup correctly!

Implements SPxRatioTester.

Definition at line 175 of file spxdefaultrt.cpp.

References SSVectorBase< R >::clearNum(), SPxSolver::coId(), SPxSolver::coPvec(), SPxRatioTester::delta, UpdateVector::delta(), SPxSolver::epsilon(), VectorBase< R >::get_const_ptr(), SPxSolver::id(), UpdateVector::idx(), IdxSet::index(), soplex::infinity, SPxSolver::isBasic(), SPxId::isValid(), SPxSolver::lcBound(), SPxSolver::lpBound(), MSG_DEBUG, SPxSolver::pVec(), SSVectorBase< R >::setup(), IdxSet::size(), SPxRatioTester::solver(), SPxSolver::ucBound(), SPxSolver::upBound(), and SSVectorBase< R >::values().

int selectLeave ( Real &  val, Real    )

virtual

Here comes the ratio test for selecting a variable to leave the basis. It is assumed that Vec.delta() and fVec.idx() have been setup correctly!

The leaving variable is selected such that the update of fVec() (using fVec.value() * fVec.delta()) keeps the basis feasible within solver()->entertol(). Hence, fVec.value() must be chosen such that one updated value of theFvec just reaches its bound and no other one exceeds them by more than solver()->entertol(). Further, fVec.value() must have the same sign as argument val.

The return value of selectLeave() is the number of a variable in the basis selected to leave the basis. -1 indicates that no variable could be selected. Otherwise, parameter val contains the chosen fVec.value().

Implements SPxRatioTester.

Definition at line 40 of file spxdefaultrt.cpp.

References ASSERT_WARN, SPxRatioTester::delta, UpdateVector::delta(), SPxSolver::epsilon(), SPxSolver::fVec(), VectorBase< R >::get_const_ptr(), UpdateVector::idx(), IdxSet::index(), soplex::infinity, SPxSolver::lbBound(), SSVectorBase< R >::setup(), IdxSet::size(), SPxRatioTester::solver(), SPxSolver::ubBound(), and SSVectorBase< R >::values().