lemon/lp_skeleton.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Sat, 20 Feb 2010 18:39:03 +0100
changeset 839 f3bc4e9b5f3a
parent 576 745e182d0139
child 877 141f9c0db4a3
permissions -rw-r--r--
New heuristics for MCF algorithms (#340)
and some implementation improvements.

- A useful heuristic is added to NetworkSimplex to make the
initial pivots faster.
- A powerful global update heuristic is added to CostScaling
and the implementation is reworked with various improvements.
- Better relabeling in CostScaling to improve numerical stability
and make the code faster.
- A small improvement is made in CapacityScaling for better
delta computation.
- Add notes to the classes about the usage of vector<char> instead
of vector<bool> for efficiency reasons.
     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) 2003-2008
     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 #include <lemon/lp_skeleton.h>
    20 
    21 ///\file
    22 ///\brief A skeleton file to implement LP solver interfaces
    23 namespace lemon {
    24 
    25   int SkeletonSolverBase::_addCol()
    26   {
    27     return ++col_num;
    28   }
    29 
    30   int SkeletonSolverBase::_addRow()
    31   {
    32     return ++row_num;
    33   }
    34 
    35   int SkeletonSolverBase::_addRow(Value, ExprIterator, ExprIterator, Value)
    36   {
    37     return ++row_num;
    38   }
    39 
    40   void SkeletonSolverBase::_eraseCol(int) {}
    41   void SkeletonSolverBase::_eraseRow(int) {}
    42 
    43   void SkeletonSolverBase::_getColName(int, std::string &) const {}
    44   void SkeletonSolverBase::_setColName(int, const std::string &) {}
    45   int SkeletonSolverBase::_colByName(const std::string&) const { return -1; }
    46 
    47   void SkeletonSolverBase::_getRowName(int, std::string &) const {}
    48   void SkeletonSolverBase::_setRowName(int, const std::string &) {}
    49   int SkeletonSolverBase::_rowByName(const std::string&) const { return -1; }
    50 
    51   void SkeletonSolverBase::_setRowCoeffs(int, ExprIterator, ExprIterator) {}
    52   void SkeletonSolverBase::_getRowCoeffs(int, InsertIterator) const {}
    53 
    54   void SkeletonSolverBase::_setColCoeffs(int, ExprIterator, ExprIterator) {}
    55   void SkeletonSolverBase::_getColCoeffs(int, InsertIterator) const {}
    56 
    57   void SkeletonSolverBase::_setCoeff(int, int, Value) {}
    58   SkeletonSolverBase::Value SkeletonSolverBase::_getCoeff(int, int) const
    59   { return 0; }
    60 
    61   void SkeletonSolverBase::_setColLowerBound(int, Value) {}
    62   SkeletonSolverBase::Value SkeletonSolverBase::_getColLowerBound(int) const
    63   {  return 0; }
    64 
    65   void SkeletonSolverBase::_setColUpperBound(int, Value) {}
    66   SkeletonSolverBase::Value SkeletonSolverBase::_getColUpperBound(int) const
    67   {  return 0; }
    68 
    69   void SkeletonSolverBase::_setRowLowerBound(int, Value) {}
    70   SkeletonSolverBase::Value SkeletonSolverBase::_getRowLowerBound(int) const
    71   {  return 0; }
    72 
    73   void SkeletonSolverBase::_setRowUpperBound(int, Value) {}
    74   SkeletonSolverBase::Value SkeletonSolverBase::_getRowUpperBound(int) const
    75   {  return 0; }
    76 
    77   void SkeletonSolverBase::_setObjCoeffs(ExprIterator, ExprIterator) {}
    78   void SkeletonSolverBase::_getObjCoeffs(InsertIterator) const {};
    79 
    80   void SkeletonSolverBase::_setObjCoeff(int, Value) {}
    81   SkeletonSolverBase::Value SkeletonSolverBase::_getObjCoeff(int) const
    82   {  return 0; }
    83 
    84   void SkeletonSolverBase::_setSense(Sense) {}
    85   SkeletonSolverBase::Sense SkeletonSolverBase::_getSense() const
    86   { return MIN; }
    87 
    88   void SkeletonSolverBase::_clear() {
    89     row_num = col_num = 0;
    90   }
    91 
    92   void SkeletonSolverBase::_messageLevel(MessageLevel) {}
    93 
    94   LpSkeleton::SolveExitStatus LpSkeleton::_solve() { return SOLVED; }
    95 
    96   LpSkeleton::Value LpSkeleton::_getPrimal(int) const { return 0; }
    97   LpSkeleton::Value LpSkeleton::_getDual(int) const { return 0; }
    98   LpSkeleton::Value LpSkeleton::_getPrimalValue() const { return 0; }
    99 
   100   LpSkeleton::Value LpSkeleton::_getPrimalRay(int) const { return 0; }
   101   LpSkeleton::Value LpSkeleton::_getDualRay(int) const { return 0; }
   102 
   103   LpSkeleton::ProblemType LpSkeleton::_getPrimalType() const
   104   { return UNDEFINED; }
   105 
   106   LpSkeleton::ProblemType LpSkeleton::_getDualType() const
   107   { return UNDEFINED; }
   108 
   109   LpSkeleton::VarStatus LpSkeleton::_getColStatus(int) const
   110   { return BASIC; }
   111 
   112   LpSkeleton::VarStatus LpSkeleton::_getRowStatus(int) const
   113   { return BASIC; }
   114 
   115   LpSkeleton* LpSkeleton::newSolver() const
   116   { return static_cast<LpSkeleton*>(0); }
   117 
   118   LpSkeleton* LpSkeleton::cloneSolver() const
   119   { return static_cast<LpSkeleton*>(0); }
   120 
   121   const char* LpSkeleton::_solverName() const { return "LpSkeleton"; }
   122 
   123   MipSkeleton::SolveExitStatus MipSkeleton::_solve()
   124   { return SOLVED; }
   125 
   126   MipSkeleton::Value MipSkeleton::_getSol(int) const { return 0; }
   127   MipSkeleton::Value MipSkeleton::_getSolValue() const { return 0; }
   128 
   129   MipSkeleton::ProblemType MipSkeleton::_getType() const
   130   { return UNDEFINED; }
   131 
   132   MipSkeleton* MipSkeleton::newSolver() const
   133   { return static_cast<MipSkeleton*>(0); }
   134 
   135   MipSkeleton* MipSkeleton::cloneSolver() const
   136   { return static_cast<MipSkeleton*>(0); }
   137 
   138   const char* MipSkeleton::_solverName() const { return "MipSkeleton"; }
   139 
   140 } //namespace lemon
   141