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/* $Id: ClpDualRowSteepest.hpp 2070 2014-11-18 11:12:54Z forrest $ */
// Copyright (C) 2002, International Business Machines
// Corporation and others. All Rights Reserved.
// This code is licensed under the terms of the Eclipse Public License (EPL).
#ifndef ClpDualRowSteepest_H
#define ClpDualRowSteepest_H
#include "ClpDualRowPivot.hpp"
class CoinIndexedVector;
//#############################################################################
/** Dual Row Pivot Steepest Edge Algorithm Class
See Forrest-Goldfarb paper for algorithm
*/
class ClpDualRowSteepest : public ClpDualRowPivot {
public:
///@name Algorithmic methods
//@{
/// Returns pivot row, -1 if none
virtual int pivotRow();
/** Updates weights and returns pivot alpha.
Also does FT update */
virtual double updateWeights(CoinIndexedVector * input,
CoinIndexedVector * spare,
CoinIndexedVector * spare2,
CoinIndexedVector * updatedColumn);
/** Updates primal solution (and maybe list of candidates)
Uses input vector which it deletes
Computes change in objective function
*/
virtual void updatePrimalSolution(CoinIndexedVector * input,
double theta,
double & changeInObjective);
/** Saves any weights round factorization as pivot rows may change
Save model
May also recompute infeasibility stuff
1) before factorization
2) after good factorization (if weights empty may initialize)
3) after something happened but no factorization
(e.g. check for infeasible)
4) as 2 but restore weights from previous snapshot
5) for strong branching - initialize (uninitialized) , infeasibilities
*/
virtual void saveWeights(ClpSimplex * model, int mode);
/// Pass in saved weights
void passInSavedWeights(const CoinIndexedVector * saved);
/// Get saved weights
inline CoinIndexedVector * savedWeights()
{ return savedWeights_;}
/// Gets rid of last update
virtual void unrollWeights();
/// Gets rid of all arrays
virtual void clearArrays();
/// Returns true if would not find any row
virtual bool looksOptimal() const;
/// Called when maximum pivots changes
virtual void maximumPivotsChanged();
//@}
/** enums for persistence
*/
enum Persistence {
normal = 0x00, // create (if necessary) and destroy
keep = 0x01 // create (if necessary) and leave
};
///@name Constructors and destructors
//@{
/** Default Constructor
0 is uninitialized, 1 full, 2 is partial uninitialized,
3 starts as 2 but may switch to 1.
By partial is meant that the weights are updated as normal
but only part of the infeasible basic variables are scanned.
This can be faster on very easy problems.
*/
ClpDualRowSteepest(int mode = 3);
/// Copy constructor
ClpDualRowSteepest(const ClpDualRowSteepest &);
/// Assignment operator
ClpDualRowSteepest & operator=(const ClpDualRowSteepest& rhs);
/// Fill most values
void fill(const ClpDualRowSteepest& rhs);
/// Destructor
virtual ~ClpDualRowSteepest ();
/// Clone
virtual ClpDualRowPivot * clone(bool copyData = true) const;
//@}
/**@name gets and sets */
//@{
/// Mode
inline int mode() const {
return mode_;
}
/// Set mode
inline void setMode(int mode) {
mode_ = mode;
}
/// Set/ get persistence
inline void setPersistence(Persistence life) {
persistence_ = life;
}
inline Persistence persistence() const {
return persistence_ ;
}
//@}
//---------------------------------------------------------------------------
private:
///@name Private member data
/** Status
0) Normal
-1) Needs initialization
1) Weights are stored by sequence number
*/
int state_;
/** If 0 then we are using uninitialized weights, 1 then full,
if 2 then uninitialized partial, 3 switchable */
int mode_;
/// Life of weights
Persistence persistence_;
/// weight array
double * weights_;
/// square of infeasibility array (just for infeasible rows)
CoinIndexedVector * infeasible_;
/// alternate weight array (so we can unroll)
CoinIndexedVector * alternateWeights_;
/// save weight array (so we can use checkpoint)
CoinIndexedVector * savedWeights_;
/// Dubious weights
int * dubiousWeights_;
//@}
};
#endif
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