include/dai/bp_dual.h

   1 /*  Copyright (C) 2009  Frederik Eaton [frederik at ofb dot net]
   2
   3     This file is part of libDAI.
   4
   5     libDAI is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     libDAI is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with libDAI; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18 */
  19
  20
  21 /// \file
  22 /// \brief Defines class BP_dual
  23 /// \todo Improve documentation
  24 /// \todo Clean up
  25
  26
  27 #ifndef __defined_libdai_bp_dual_h
  28 #define __defined_libdai_bp_dual_h
  29
  30
  31 #include <dai/daialg.h>
  32 #include <dai/factorgraph.h>
  33 #include <dai/enum.h>
  34
  35
  36 namespace dai {
  37
  38
  39 /** Class to estimate "dual" versions of BP messages, and normalizers, given an InfAlg.
  40  *  These are computed from the variable and factor beliefs of the InfAlg.
  41  *  This class is used primarily by BBP.
  42  */
  43 class BP_dual {
  44
  45 protected:
  46     template<class T>
  47     struct _edges_t : public std::vector<std::vector<T> > {};
  48
  49     struct messages {
  50         // messages:
  51         _edges_t<Prob> n;
  52         _edges_t<Real> Zn;
  53         _edges_t<Prob> m;
  54         _edges_t<Real> Zm;
  55     };
  56     messages _msgs;
  57
  58     struct beliefs {
  59         // beliefs:
  60         // indexed by node
  61         std::vector<Prob> b1;
  62         std::vector<Real> Zb1;
  63         // indexed by factor
  64         std::vector<Prob> b2;
  65         std::vector<Real> Zb2;
  66     };
  67     beliefs _beliefs;
  68
  69     const InfAlg *_ia;
  70
  71     void Init();
  72
  73     void RegenerateMessages();
  74     void RegenerateBeliefs();
  75
  76     void CalcMessages();
  77     void CalcBeliefV(size_t i);
  78     void CalcBeliefF(size_t I);
  79     void CalcBeliefs();
  80
  81     void calcNewM(size_t i, size_t _I);
  82     void calcNewN(size_t i, size_t _I);
  83 public:
  84
  85     /// Construct BP_dual object from (converged) InfAlg object's beliefs and factors.
  86     /*  A pointer to the the InfAlg object is
  87      *  stored, so the object must not be destroyed before the BP_dual
  88      */
  89     BP_dual(const InfAlg *ia) : _ia(ia) {
  90         Init();
  91     }
  92
  93     const FactorGraph& fg() const { return _ia->fg(); }
  94
  95     /// msgM: factor -> var messages
  96     DAI_ACCMUT(Prob & msgM(size_t i, size_t _I), { return _msgs.m[i][_I]; });
  97     /// msgN: var -> factor messages
  98     DAI_ACCMUT(Prob & msgN(size_t i, size_t _I), { return _msgs.n[i][_I]; });
  99     /// Normalizer for msgM
 100     DAI_ACCMUT(Real & zM(size_t i, size_t _I), { return _msgs.Zm[i][_I]; });
 101     /// Normalizer for msgN
 102     DAI_ACCMUT(Real & zN(size_t i, size_t _I), { return _msgs.Zn[i][_I]; });
 103
 104     /// Variable beliefs
 105     Factor beliefV(size_t i) const { return Factor(_ia->fg().var(i), _beliefs.b1[i]); }
 106     /// Factor beliefs
 107     Factor beliefF(size_t I) const { return Factor(_ia->fg().factor(I).vars(), _beliefs.b2[I]); }
 108
 109     /// Normalizer for variable beliefs
 110     Real beliefVZ(size_t i) const { return _beliefs.Zb1[i]; }
 111     /// Normalizer for factor beliefs
 112     Real beliefFZ(size_t I) const { return _beliefs.Zb2[I]; }
 113
 114 };
 115
 116
 117 } // end of namespace dai
 118
 119
 120 #endif