Cgl  0.60.3
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
Classes | Public Member Functions | Static Public Member Functions | Private Member Functions | Private Attributes | List of all members
implied_free_action Class Reference

Detect and process implied free variables. More...

#include <CoinPresolveImpliedFree.hpp>

+ Inheritance diagram for implied_free_action:
+ Collaboration diagram for implied_free_action:


struct  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 ~implied_free_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, int &fillLevel)
- Static Public Member Functions inherited from CoinPresolveAction
static void throwCoinError (const char *error, const char *ps_routine)
 Stub routine to throw exceptions. More...

Private Member Functions

 implied_free_action (int nactions, const action *actions, const CoinPresolveAction *next)

Private Attributes

const int nactions_
const action *const actions_

Additional Inherited Members

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

Detailed Description

Detect and process implied free variables.

Consider a singleton variable x (i.e., a variable involved in only one constraint). Suppose that the bounds on that constraint, combined with the bounds on the other variables involved in the constraint, are such that even the worst case values of the other variables still imply bounds for x which are tighter than the variable's original bounds. Since x can never reach its upper or lower bounds, it is an implied free variable. Both x and the constraint can be deleted from the problem.

A similar transform for the case where the variable is not a natural column singleton is handled by subst_constraint_action.

Definition at line 29 of file CoinPresolveImpliedFree.hpp.

Constructor & Destructor Documentation

implied_free_action::implied_free_action ( int  nactions,
const action actions,
const CoinPresolveAction next 

Definition at line 42 of file CoinPresolveImpliedFree.hpp.

virtual implied_free_action::~implied_free_action ( )

Member Function Documentation

const char* implied_free_action::name ( ) const

A name for debug printing.

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

Implements CoinPresolveAction.

static const CoinPresolveAction* implied_free_action::presolve ( CoinPresolveMatrix prob,
const CoinPresolveAction next,
int &  fillLevel 
void implied_free_action::postsolve ( CoinPostsolveMatrix prob) const

Apply the postsolve transformation for this particular presolve action.

Implements CoinPresolveAction.

Member Data Documentation

const int implied_free_action::nactions_

Definition at line 39 of file CoinPresolveImpliedFree.hpp.

const action* const implied_free_action::actions_

Definition at line 40 of file CoinPresolveImpliedFree.hpp.

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