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SoPlex

Sequential object-oriented simPlex

SPxWeightST< R > Class Template Reference

Weighted start basis.Class SPxWeightST is an implementation of a SPxStarter for generating a Simplex starting basis. Using method setupWeights() it sets up arrays weight and coWeight, or equivalently rowWeight and colWeight. (rowWeight and colWeight are just pointers initialized to weight and coWeight according to the representation of SoPlex base passed to method generate().) More...

#include <spxweightst.h>

Public Member Functions

Construction / destruction
 SPxWeightST ()
 default constructor. More...
 
 SPxWeightST (const SPxWeightST &old)
 copy constructor More...
 
SPxWeightSToperator= (const SPxWeightST &rhs)
 assignment operator More...
 
virtual ~SPxWeightST ()
 destructor. More...
 
virtual SPxStarter< R > * clone () const
 clone function for polymorphism More...
 
Generation of a start basis
void generate (SPxSolverBase< R > &base)
 generates start basis for loaded basis. More...
 
Debugging
virtual bool isConsistent () const
 consistency check. More...
 
- Public Member Functions inherited from SPxStarter< R >
virtual const char * getName () const
 get name of starter. More...
 
 SPxStarter (const char *name)
 constructor More...
 
 SPxStarter (const SPxStarter &old)
 copy constructor More...
 
SPxStarteroperator= (const SPxStarter &rhs)
 assignment operator More...
 
virtual ~SPxStarter ()
 destructor. More...
 

Protected Member Functions

Protected helpers
virtual void setupWeights (SPxSolverBase< R > &base)
 sets up variable weights. More...
 

Protected Attributes

Protected data
Array< R > rowWeight
 weight value for LP rows. More...
 
Array< R > colWeight
 weight value for LP columns. More...
 
DataArray< bool > rowRight
 set variable to rhs?. More...
 
DataArray< bool > colUp
 set primal variable to upper bound. More...
 
- Protected Attributes inherited from SPxStarter< R >
const char * m_name
 name of the starter More...
 

Private Member Functions

Private helpers
void setPrimalStatus (typename SPxBasisBase< R >::Desc &, const SPxSolverBase< R > &, const SPxId &)
 

Private Attributes

Private data
DataArray< int > forbidden
 
Array< R > * weight
 
Array< R > * coWeight
 

Detailed Description

template<class R>
class soplex::SPxWeightST< R >

Weighted start basis.

Class SPxWeightST is an implementation of a SPxStarter for generating a Simplex starting basis. Using method setupWeights() it sets up arrays weight and coWeight, or equivalently rowWeight and colWeight. (rowWeight and colWeight are just pointers initialized to weight and coWeight according to the representation of SoPlex base passed to method generate().)

The weight values are then used to setup a starting basis for the LP: vectors with low values are likely to become dual (i.e. basic for a column basis) and such with high values are likely to become primal (i.e. nonbasic for a column basis).

However, if a variable having an upper and lower bound is to become primal, there is still a choice for setting it either to its upper or lower bound. Members rowRight and colUp are used to determine where to set a primal variable. If rowRight[i] is set to a nonzero value, the right-hand side inequality is set tightly for the i 'th to become primal. Analogously, If colUp[j] is nonzero, the j 'th variable will be set to its upper bound if it becomes primal.

Definition at line 57 of file spxweightst.h.

Constructor & Destructor Documentation

◆ SPxWeightST() [1/2]

default constructor.

Definition at line 111 of file spxweightst.h.

References SPxWeightST< R >::isConsistent().

Referenced by SPxWeightST< R >::clone().

◆ SPxWeightST() [2/2]

◆ ~SPxWeightST()

virtual ~SPxWeightST ( )
virtual

destructor.

Definition at line 176 of file spxweightst.h.

Member Function Documentation

◆ clone()

virtual SPxStarter<R>* clone ( ) const
virtual

clone function for polymorphism

Implements SPxStarter< R >.

Reimplemented in SPxVectorST< R >, and SPxSumST< R >.

Definition at line 182 of file spxweightst.h.

References SPxWeightST< R >::generate(), SPxWeightST< R >::isConsistent(), and SPxWeightST< R >::SPxWeightST().

◆ generate()

void generate ( SPxSolverBase< R > &  base)
virtual

generates start basis for loaded basis.

Implements SPxStarter< R >.

Referenced by SPxWeightST< R >::clone().

◆ isConsistent()

◆ operator=()

◆ setPrimalStatus()

void setPrimalStatus ( typename SPxBasisBase< R >::Desc &  ,
const SPxSolverBase< R > &  ,
const SPxId  
)
private

◆ setupWeights()

virtual void setupWeights ( SPxSolverBase< R > &  base)
protectedvirtual

sets up variable weights.

This method is called in order to setup the weights for all variables. It has been declared virtual in order to allow for derived classes to compute other weight values.

Reimplemented in SPxVectorST< R >, and SPxSumST< R >.

Member Data Documentation

◆ colUp

DataArray< bool > colUp
protected

set primal variable to upper bound.

Definition at line 91 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=().

◆ colWeight

Array< R > colWeight
protected

weight value for LP columns.

Definition at line 87 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=(), and SPxWeightST< R >::SPxWeightST().

◆ coWeight

Array< R >* coWeight
private

Definition at line 69 of file spxweightst.h.

◆ forbidden

DataArray< int > forbidden
private

Definition at line 65 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=().

◆ rowRight

DataArray< bool > rowRight
protected

set variable to rhs?.

Definition at line 89 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=().

◆ rowWeight

Array< R > rowWeight
protected

weight value for LP rows.

Definition at line 85 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=(), and SPxWeightST< R >::SPxWeightST().

◆ weight

Array< R >* weight
private

Definition at line 67 of file spxweightst.h.

Referenced by SPxWeightST< R >::operator=(), and SPxWeightST< R >::SPxWeightST().