CoinUtils  2.10.13
Classes | Public Member Functions | Static Public Member Functions | List of all members
dupcol_action Class Reference

Detect and remove duplicate columns. More...

#include <CoinPresolveDupcol.hpp>

+ Inheritance diagram for dupcol_action:

Public Member Functions

const char * name () const
 A name for debug printing. More...
 
void postsolve (CoinPostsolveMatrix *prob) const
 Apply the postsolve transformation for this particular presolve action. More...
 
virtual ~dupcol_action ()
 
- Public Member Functions inherited from CoinPresolveAction
 CoinPresolveAction (const CoinPresolveAction *next)
 Construct a postsolve object and add it to the transformation list. More...
 
void setNext (const CoinPresolveAction *nextAction)
 modify next (when building rather than passing) More...
 
virtual ~CoinPresolveAction ()
 Virtual destructor. More...
 

Static Public Member Functions

static const CoinPresolveActionpresolve (CoinPresolveMatrix *prob, const CoinPresolveAction *next)
 
- Static Public Member Functions inherited from CoinPresolveAction
static void throwCoinError (const char *error, const char *ps_routine)
 Stub routine to throw exceptions. More...
 

Additional Inherited Members

- Public Attributes inherited from CoinPresolveAction
const CoinPresolveActionnext
 The next presolve transformation. More...
 

Detailed Description

Detect and remove duplicate columns.

The general technique is to sum the coefficients a_(*,j) of each column. Columns with identical sums are duplicates. The obvious problem is that, e.g., [1 0 1 0] and [0 1 0 1] both add to 2. To minimize the chances of false positives, the coefficients of each row are multipled by a random number r_i, so that we sum r_i*a_ij.

Candidate columns are checked to confirm they are identical. Where the columns have the same objective coefficient, the two are combined. If the columns have different objective coefficients, complications ensue. In order to remove the duplicate, it must be possible to fix the variable at a bound.

Definition at line 32 of file CoinPresolveDupcol.hpp.

Constructor & Destructor Documentation

◆ ~dupcol_action()

virtual dupcol_action::~dupcol_action ( )
virtual

Member Function Documentation

◆ name()

const char* dupcol_action::name ( ) const
virtual

A name for debug printing.

It is expected that the name is not stored in the transform itself.

Implements CoinPresolveAction.

◆ presolve()

static const CoinPresolveAction* dupcol_action::presolve ( CoinPresolveMatrix prob,
const CoinPresolveAction next 
)
static

◆ postsolve()

void dupcol_action::postsolve ( CoinPostsolveMatrix prob) const
virtual

Apply the postsolve transformation for this particular presolve action.

Implements CoinPresolveAction.


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