lemon/lp_skeleton.h
author Peter Kovacs <kpeter@inf.elte.hu>
Tue, 15 Mar 2011 19:32:21 +0100
changeset 936 ddd3c0d3d9bf
parent 746 e4554cd6b2bf
child 1063 1782aa72495a
permissions -rw-r--r--
Implement the scaling Price Refinement heuristic in CostScaling (#417)
instead of Early Termination.

These two heuristics are similar, but the newer one is faster
and not only makes it possible to skip some epsilon phases, but
it can improve the performance of the other phases, as well.
     1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library.
     4  *
     5  * Copyright (C) 2003-2010
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 #ifndef LEMON_LP_SKELETON_H
    20 #define LEMON_LP_SKELETON_H
    21 
    22 #include <lemon/lp_base.h>
    23 
    24 ///\file
    25 ///\brief Skeleton file to implement LP/MIP solver interfaces
    26 ///
    27 ///The classes in this file do nothing, but they can serve as skeletons when
    28 ///implementing an interface to new solvers.
    29 namespace lemon {
    30 
    31   ///A skeleton class to implement LP/MIP solver base interface
    32 
    33   ///This class does nothing, but it can serve as a skeleton when
    34   ///implementing an interface to new solvers.
    35   class SkeletonSolverBase : public virtual LpBase {
    36     int col_num,row_num;
    37 
    38   protected:
    39 
    40     SkeletonSolverBase()
    41       : col_num(-1), row_num(-1) {}
    42 
    43     /// \e
    44     virtual int _addCol();
    45     /// \e
    46     virtual int _addRow();
    47     /// \e
    48     virtual int _addRow(Value l, ExprIterator b, ExprIterator e, Value u);
    49     /// \e
    50     virtual void _eraseCol(int i);
    51     /// \e
    52     virtual void _eraseRow(int i);
    53 
    54     /// \e
    55     virtual void _getColName(int col, std::string& name) const;
    56     /// \e
    57     virtual void _setColName(int col, const std::string& name);
    58     /// \e
    59     virtual int _colByName(const std::string& name) const;
    60 
    61     /// \e
    62     virtual void _getRowName(int row, std::string& name) const;
    63     /// \e
    64     virtual void _setRowName(int row, const std::string& name);
    65     /// \e
    66     virtual int _rowByName(const std::string& name) const;
    67 
    68     /// \e
    69     virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
    70     /// \e
    71     virtual void _getRowCoeffs(int i, InsertIterator b) const;
    72     /// \e
    73     virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
    74     /// \e
    75     virtual void _getColCoeffs(int i, InsertIterator b) const;
    76 
    77     /// Set one element of the coefficient matrix
    78     virtual void _setCoeff(int row, int col, Value value);
    79 
    80     /// Get one element of the coefficient matrix
    81     virtual Value _getCoeff(int row, int col) const;
    82 
    83     /// The lower bound of a variable (column) have to be given by an
    84     /// extended number of type Value, i.e. a finite number of type
    85     /// Value or -\ref INF.
    86     virtual void _setColLowerBound(int i, Value value);
    87     /// \e
    88 
    89     /// The lower bound of a variable (column) is an
    90     /// extended number of type Value, i.e. a finite number of type
    91     /// Value or -\ref INF.
    92     virtual Value _getColLowerBound(int i) const;
    93 
    94     /// The upper bound of a variable (column) have to be given by an
    95     /// extended number of type Value, i.e. a finite number of type
    96     /// Value or \ref INF.
    97     virtual void _setColUpperBound(int i, Value value);
    98     /// \e
    99 
   100     /// The upper bound of a variable (column) is an
   101     /// extended number of type Value, i.e. a finite number of type
   102     /// Value or \ref INF.
   103     virtual Value _getColUpperBound(int i) const;
   104 
   105     /// The lower bound of a constraint (row) have to be given by an
   106     /// extended number of type Value, i.e. a finite number of type
   107     /// Value or -\ref INF.
   108     virtual void _setRowLowerBound(int i, Value value);
   109     /// \e
   110 
   111     /// The lower bound of a constraint (row) is an
   112     /// extended number of type Value, i.e. a finite number of type
   113     /// Value or -\ref INF.
   114     virtual Value _getRowLowerBound(int i) const;
   115 
   116     /// The upper bound of a constraint (row) have to be given by an
   117     /// extended number of type Value, i.e. a finite number of type
   118     /// Value or \ref INF.
   119     virtual void _setRowUpperBound(int i, Value value);
   120     /// \e
   121 
   122     /// The upper bound of a constraint (row) is an
   123     /// extended number of type Value, i.e. a finite number of type
   124     /// Value or \ref INF.
   125     virtual Value _getRowUpperBound(int i) const;
   126 
   127     /// \e
   128     virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
   129     /// \e
   130     virtual void _getObjCoeffs(InsertIterator b) const;
   131 
   132     /// \e
   133     virtual void _setObjCoeff(int i, Value obj_coef);
   134     /// \e
   135     virtual Value _getObjCoeff(int i) const;
   136 
   137     ///\e
   138     virtual void _setSense(Sense);
   139     ///\e
   140     virtual Sense _getSense() const;
   141 
   142     ///\e
   143     virtual void _clear();
   144 
   145     ///\e
   146     virtual void _messageLevel(MessageLevel);
   147   };
   148 
   149   /// \brief Skeleton class for an LP solver interface
   150   ///
   151   ///This class does nothing, but it can serve as a skeleton when
   152   ///implementing an interface to new solvers.
   153 
   154   ///\ingroup lp_group
   155   class LpSkeleton : public LpSolver, public SkeletonSolverBase {
   156   public:
   157     ///\e
   158     LpSkeleton() : LpSolver(), SkeletonSolverBase() {}
   159     ///\e
   160     virtual LpSkeleton* newSolver() const;
   161     ///\e
   162     virtual LpSkeleton* cloneSolver() const;
   163   protected:
   164 
   165     ///\e
   166     virtual SolveExitStatus _solve();
   167 
   168     ///\e
   169     virtual Value _getPrimal(int i) const;
   170     ///\e
   171     virtual Value _getDual(int i) const;
   172 
   173     ///\e
   174     virtual Value _getPrimalValue() const;
   175 
   176     ///\e
   177     virtual Value _getPrimalRay(int i) const;
   178     ///\e
   179     virtual Value _getDualRay(int i) const;
   180 
   181     ///\e
   182     virtual ProblemType _getPrimalType() const;
   183     ///\e
   184     virtual ProblemType _getDualType() const;
   185 
   186     ///\e
   187     virtual VarStatus _getColStatus(int i) const;
   188     ///\e
   189     virtual VarStatus _getRowStatus(int i) const;
   190 
   191     ///\e
   192     virtual const char* _solverName() const;
   193 
   194   };
   195 
   196   /// \brief Skeleton class for a MIP solver interface
   197   ///
   198   ///This class does nothing, but it can serve as a skeleton when
   199   ///implementing an interface to new solvers.
   200   ///\ingroup lp_group
   201   class MipSkeleton : public MipSolver, public SkeletonSolverBase {
   202   public:
   203     ///\e
   204     MipSkeleton() : MipSolver(), SkeletonSolverBase() {}
   205     ///\e
   206     virtual MipSkeleton* newSolver() const;
   207     ///\e
   208     virtual MipSkeleton* cloneSolver() const;
   209 
   210   protected:
   211     ///\e
   212     virtual SolveExitStatus _solve();
   213 
   214     ///\e
   215     virtual Value _getSol(int i) const;
   216 
   217     ///\e
   218     virtual Value _getSolValue() const;
   219 
   220     ///\e
   221     virtual ProblemType _getType() const;
   222 
   223     ///\e
   224     virtual const char* _solverName() const;
   225   };
   226 
   227 } //namespace lemon
   228 
   229 #endif