source: trunk/Cbc/src/CbcHeuristicDiveFractional.cpp @ 1424

Last change on this file since 1424 was 1286, checked in by EdwinStraver, 10 years ago

Changed formatting using AStyle -A4 -p

File size: 3.3 KB
Line 
1/* $Id: CbcHeuristicDiveFractional.cpp 1173 2009-06-04 09:44:10Z forrest $ */
2// Copyright (C) 2008, International Business Machines
3// Corporation and others.  All Rights Reserved.
4#if defined(_MSC_VER)
5// Turn off compiler warning about long names
6#  pragma warning(disable:4786)
7#endif
8
9#include "CbcHeuristicDiveFractional.hpp"
10#include "CbcStrategy.hpp"
11
12// Default Constructor
13CbcHeuristicDiveFractional::CbcHeuristicDiveFractional()
14        : CbcHeuristicDive()
15{
16}
17
18// Constructor from model
19CbcHeuristicDiveFractional::CbcHeuristicDiveFractional(CbcModel & model)
20        : CbcHeuristicDive(model)
21{
22}
23
24// Destructor
25CbcHeuristicDiveFractional::~CbcHeuristicDiveFractional ()
26{
27}
28
29// Clone
30CbcHeuristicDiveFractional *
31CbcHeuristicDiveFractional::clone() const
32{
33    return new CbcHeuristicDiveFractional(*this);
34}
35
36// Create C++ lines to get to current state
37void
38CbcHeuristicDiveFractional::generateCpp( FILE * fp)
39{
40    CbcHeuristicDiveFractional other;
41    fprintf(fp, "0#include \"CbcHeuristicDiveFractional.hpp\"\n");
42    fprintf(fp, "3  CbcHeuristicDiveFractional heuristicDiveFractional(*cbcModel);\n");
43    CbcHeuristic::generateCpp(fp, "heuristicDiveFractional");
44    fprintf(fp, "3  cbcModel->addHeuristic(&heuristicDiveFractional);\n");
45}
46
47// Copy constructor
48CbcHeuristicDiveFractional::CbcHeuristicDiveFractional(const CbcHeuristicDiveFractional & rhs)
49        :
50        CbcHeuristicDive(rhs)
51{
52}
53
54// Assignment operator
55CbcHeuristicDiveFractional &
56CbcHeuristicDiveFractional::operator=( const CbcHeuristicDiveFractional & rhs)
57{
58    if (this != &rhs) {
59        CbcHeuristicDive::operator=(rhs);
60    }
61    return *this;
62}
63
64bool
65CbcHeuristicDiveFractional::selectVariableToBranch(OsiSolverInterface* solver,
66        const double* newSolution,
67        int& bestColumn,
68        int& bestRound)
69{
70    int numberIntegers = model_->numberIntegers();
71    const int * integerVariable = model_->integerVariable();
72    double integerTolerance = model_->getDblParam(CbcModel::CbcIntegerTolerance);
73
74    bestColumn = -1;
75    bestRound = -1; // -1 rounds down, +1 rounds up
76    double bestFraction = DBL_MAX;
77    bool allTriviallyRoundableSoFar = true;
78    for (int i = 0; i < numberIntegers; i++) {
79        int iColumn = integerVariable[i];
80        double value = newSolution[iColumn];
81        double fraction = value - floor(value);
82        int round = 0;
83        if (fabs(floor(value + 0.5) - value) > integerTolerance) {
84            if (allTriviallyRoundableSoFar || (downLocks_[i] > 0 && upLocks_[i] > 0)) {
85
86                if (allTriviallyRoundableSoFar && downLocks_[i] > 0 && upLocks_[i] > 0) {
87                    allTriviallyRoundableSoFar = false;
88                    bestFraction = DBL_MAX;
89                }
90
91                // the variable cannot be rounded
92                if (fraction < 0.5)
93                    round = -1;
94                else {
95                    round = 1;
96                    fraction = 1.0 - fraction;
97                }
98
99                // if variable is not binary, penalize it
100                if (!solver->isBinary(iColumn))
101                    fraction *= 1000.0;
102
103                if (fraction < bestFraction) {
104                    bestColumn = iColumn;
105                    bestFraction = fraction;
106                    bestRound = round;
107                }
108            }
109        }
110    }
111    return allTriviallyRoundableSoFar;
112}
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