src/mr.cpp

   1 /*  Copyright (C) 2006-2008  Joris Mooij  [joris dot mooij at tuebingen dot mpg dot de]
   2     Radboud University Nijmegen, The Netherlands /
   3     Max Planck Institute for Biological Cybernetics, Germany
   4
   5     This file is part of libDAI.
   6
   7     libDAI is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     libDAI is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with libDAI; if not, write to the Free Software
  19     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  20 */
  21
  22
  23 #include <cstdio>
  24 #include <ctime>
  25 #include <cmath>
  26 #include <cstdlib>
  27 #include <dai/mr.h>
  28 #include <dai/bp.h>
  29 #include <dai/jtree.h>
  30 #include <dai/util.h>
  31 #include <dai/diffs.h>
  32
  33
  34 namespace dai {
  35
  36
  37 using namespace std;
  38
  39
  40 const char *MR::Name = "MR";
  41
  42
  43 void MR::setProperties( const PropertySet &opts ) {
  44     assert( opts.hasKey("tol") );
  45     assert( opts.hasKey("verbose") );
  46     assert( opts.hasKey("updates") );
  47     assert( opts.hasKey("inits") );
  48
  49     props.tol = opts.getStringAs<double>("tol");
  50     props.verbose = opts.getStringAs<size_t>("verbose");
  51     props.updates = opts.getStringAs<Properties::UpdateType>("updates");
  52     props.inits = opts.getStringAs<Properties::InitType>("inits");
  53 }
  54
  55
  56 PropertySet MR::getProperties() const {
  57     PropertySet opts;
  58     opts.Set( "tol", props.tol );
  59     opts.Set( "verbose", props.verbose );
  60     opts.Set( "updates", props.updates );
  61     opts.Set( "inits", props.inits );
  62     return opts;
  63 }
  64
  65
  66 string MR::printProperties() const {
  67     stringstream s( stringstream::out );
  68     s << "[";
  69     s << "tol=" << props.tol << ",";
  70     s << "verbose=" << props.verbose << ",";
  71     s << "updates=" << props.updates << ",";
  72     s << "inits=" << props.inits << "]";
  73     return s.str();
  74 }
  75
  76
  77 // init N, con, nb, tJ, theta
  78 void MR::init(size_t Nin, double *_w, double *_th) {
  79     size_t i,j;
  80
  81     N = Nin;
  82
  83     con.resize(N);
  84     nb.resize(N);
  85     tJ.resize(N);
  86     for(i=0; i<N; i++ ) {
  87         nb[i].resize(kmax);
  88         tJ[i].resize(kmax);
  89         con[i]=0;
  90         for(j=0; j<N; j++ )
  91             if( _w[i*N+j] != 0.0 ) {
  92                 nb[i][con[i]] = j;
  93                 tJ[i][con[i]] = tanh(_w[i*N+j]);
  94                 con[i]++;
  95             }
  96     }
  97
  98     theta.resize(N);
  99     for(i=0; i<N; i++)
 100       theta[i] = _th[i];
 101 }
 102
 103
 104 // calculate cors
 105 double MR::init_cor_resp() {
 106     size_t j,k,l, runx,i2;
 107     double variab1, variab2;
 108     double md, maxdev;
 109     double thbJsite[kmax];
 110     double xinter;
 111     double rinter;
 112     double res[kmax];
 113     size_t s2;
 114     size_t flag;
 115     size_t concav;
 116     size_t runs = 3000;
 117     double eps = 0.2;
 118     size_t cavity;
 119
 120     vector<vector<double> > tJ_org;
 121     vector<vector<size_t> > nb_org;
 122     vector<size_t> con_org;
 123     vector<double> theta_org;
 124
 125     vector<double> xfield(N*kmax,0.0);
 126     vector<double> rfield(N*kmax,0.0);
 127     vector<double> Hfield(N,0.0);
 128     vector<double> devs(N*kmax,0.0);
 129     vector<double> devs2(N*kmax,0.0);
 130     vector<double> dev(N,0.0);
 131     vector<double> avmag(N,0.0);
 132
 133     // save original tJ, nb
 134     nb_org = nb;
 135     tJ_org = tJ;
 136     con_org = con;
 137     theta_org = theta;
 138
 139     maxdev = 0.0;
 140     for(cavity=0; cavity<N; cavity++){    // for each spin to be removed
 141         con = con_org;
 142         concav=con[cavity];
 143
 144         nb = nb_org;
 145         tJ = tJ_org;
 146
 147         //  Adapt the graph variables nb[], tJ[] and con[]
 148         for(size_t i=0; i<con[cavity]; i++) {
 149             size_t ij = nb[cavity][i];
 150             flag=0;
 151             j=0;
 152             do{
 153                 if(nb[ij][j]==cavity){
 154                     while(j<(con[ij]-1)){
 155                         nb[ij][j]=nb[ij][j+1];
 156                         tJ[ij][j] = tJ[ij][j+1];
 157                         j++;
 158                     }
 159                 flag=1;
 160                 }
 161                 j++;
 162             } while(flag==0);
 163         }
 164         for(size_t i=0; i<con[cavity]; i++)
 165             con[nb[cavity][i]]--;
 166         con[cavity] = 0;
 167
 168
 169         // Do everything starting from the new graph********
 170
 171         makekindex();
 172         theta = theta_org;
 173
 174         for(size_t i=0; i<kmax*N; i++)
 175             xfield[i] = 3.0*(2*rnd_uniform()-1.);
 176
 177         for(i2=0; i2<concav; i2++){ // Subsequently apply a field to each cavity spin ****************
 178
 179             s2 = nb[cavity][i2];    // identify the index of the cavity spin
 180             for(size_t i=0; i<con[s2]; i++)
 181                 rfield[kmax*s2+i] = 1.;
 182
 183             runx=0;
 184             do {      // From here start the response and belief propagation
 185                 runx++;
 186                 md=0.0;
 187                 for(k=0; k<N; k++){
 188                     if(k!=cavity) {
 189                         for(size_t i=0; i<con[k]; i++)
 190                             thbJsite[i] = tJ[k][i];
 191                         for(l=0; l<con[k]; l++){
 192                             xinter = 1.;
 193                             rinter = 0.;
 194                             if(k==s2) rinter += 1.;
 195                             for(j=0; j<con[k]; j++)
 196                                 if(j!=l){
 197                                     variab2 = tanh(xfield[kmax*nb[k][j]+kindex[k][j]]);
 198                                     variab1 = thbJsite[j]*variab2;
 199                                     xinter *= (1.+variab1)/(1.-variab1);
 200
 201                                     rinter += thbJsite[j]*rfield[kmax*nb[k][j]+kindex[k][j]]*(1-variab2*variab2)/(1-variab1*variab1);
 202                                 }
 203
 204                             variab1 = 0.5*log(xinter);
 205                             xinter = variab1 + theta[k];
 206                             devs[kmax*k+l] = xinter-xfield[kmax*k+l];
 207                             xfield[kmax*k+l] = xfield[kmax*k+l]+devs[kmax*k+l]*eps;
 208                             if( fabs(devs[kmax*k+l]) > md )
 209                                 md = fabs(devs[kmax*k+l]);
 210
 211                             devs2[kmax*k+l] = rinter-rfield[kmax*k+l];
 212                             rfield[kmax*k+l] = rfield[kmax*k+l]+devs2[kmax*k+l]*eps;
 213                             if( fabs(devs2[kmax*k+l]) > md )
 214                                 md = fabs(devs2[kmax*k+l]);
 215                         }
 216                     }
 217                 }
 218             } while((md > props.tol)&&(runx<runs)); // Precision condition reached -> BP and RP finished
 219             if(runx==runs)
 220                 if( props.verbose >= 2 )
 221                     cout << "init_cor_resp: Convergence not reached (md=" << md << ")..." << endl;
 222             if(md > maxdev)
 223                 maxdev = md;
 224
 225             // compute the observables (i.e. magnetizations and responses)******
 226
 227             for(size_t i=0; i<concav; i++){
 228                 rinter = 0.;
 229                 xinter = 1.;
 230                 if(i!=i2)
 231                     for(j=0; j<con[nb[cavity][i]]; j++){
 232                         variab2 = tanh(xfield[kmax*nb[nb[cavity][i]][j]+kindex[nb[cavity][i]][j]]);
 233                         variab1 = tJ[nb[cavity][i]][j]*variab2;
 234                         rinter +=  tJ[nb[cavity][i]][j]*rfield[kmax*nb[nb[cavity][i]][j]+kindex[nb[cavity][i]][j]]*(1-variab2*variab2)/(1-variab1*variab1);
 235                         xinter *= (1.+variab1)/(1.-variab1);
 236                     }
 237                 xinter = tanh(0.5*log(xinter)+theta[nb[cavity][i]]);
 238                 res[i] = rinter*(1-xinter*xinter);
 239             }
 240
 241             // *******************
 242
 243             for(size_t i=0; i<concav; i++)
 244                 if(nb[cavity][i]!=s2)
 245             //      if(i!=i2)
 246                     cors[cavity][i2][i] = res[i];
 247                 else
 248                     cors[cavity][i2][i] = 0;
 249         } // close for i2 = 0...concav
 250     }
 251
 252     // restore nb, tJ, con
 253     tJ = tJ_org;
 254     nb = nb_org;
 255     con = con_org;
 256     theta = theta_org;
 257
 258     return maxdev;
 259 }
 260
 261
 262 double MR::T(size_t i, sub_nb A) {
 263     // i is a variable index
 264     // A is a subset of nb[i]
 265     //
 266     // calculate T{(i)}_A as defined in Rizzo&Montanari e-print (2.17)
 267
 268     sub_nb _nbi_min_A(con[i]);
 269     _nbi_min_A.set();
 270     _nbi_min_A &= ~A;
 271
 272     double res = theta[i];
 273     for( size_t _j = 0; _j < _nbi_min_A.size(); _j++ )
 274         if( _nbi_min_A.test(_j) )
 275             res += atanh(tJ[i][_j] * M[i][_j]);
 276     return tanh(res);
 277 }
 278
 279
 280 double MR::T(size_t i, size_t _j) {
 281     sub_nb j(con[i]);
 282     j.set(_j);
 283     return T(i,j);
 284 }
 285
 286
 287 double MR::Omega(size_t i, size_t _j, size_t _l) {
 288     sub_nb jl(con[i]);
 289     jl.set(_j);
 290     jl.set(_l);
 291     double Tijl = T(i,jl);
 292     return Tijl / (1.0 + tJ[i][_l] * M[i][_l] * Tijl);
 293 }
 294
 295
 296 double MR::Gamma(size_t i, size_t _j, size_t _l1, size_t _l2) {
 297     sub_nb jll(con[i]);
 298     jll.set(_j);
 299     double Tij = T(i,jll);
 300     jll.set(_l1);
 301     jll.set(_l2);
 302     double Tijll = T(i,jll);
 303
 304     return (Tijll - Tij) / (1.0 + tJ[i][_l1] * tJ[i][_l2] * M[i][_l1] * M[i][_l2] + tJ[i][_l1] * M[i][_l1] * Tijll + tJ[i][_l2] * M[i][_l2] * Tijll);
 305 }
 306
 307
 308 double MR::Gamma(size_t i, size_t _l1, size_t _l2) {
 309     sub_nb ll(con[i]);
 310     double Ti = T(i,ll);
 311     ll.set(_l1);
 312     ll.set(_l2);
 313     double Till = T(i,ll);
 314
 315     return (Till - Ti) / (1.0 + tJ[i][_l1] * tJ[i][_l2] * M[i][_l1] * M[i][_l2] + tJ[i][_l1] * M[i][_l1] * Till + tJ[i][_l2] * M[i][_l2] * Till);
 316 }
 317
 318
 319 double MR::_tJ(size_t i, sub_nb A) {
 320     // i is a variable index
 321     // A is a subset of nb[i]
 322     //
 323     // calculate the product of all tJ[i][_j] for _j in A
 324
 325     sub_nb::size_type _j = A.find_first();
 326     if( _j == sub_nb::npos )
 327         return 1.0;
 328     else
 329         return tJ[i][_j] * _tJ(i, A.reset(_j));
 330 }
 331
 332
 333 double MR::appM(size_t i, sub_nb A) {
 334     // i is a variable index
 335     // A is a subset of nb[i]
 336     //
 337     // calculate the moment of variables in A from M and cors, neglecting higher order cumulants,
 338     // defined as the sum over all partitions of A into subsets of cardinality two at most of the
 339     // product of the cumulants (either first order, i.e. M, or second order, i.e. cors) of the
 340     // entries of the partitions
 341
 342     sub_nb::size_type _j = A.find_first();
 343     if( _j == sub_nb::npos )
 344         return 1.0;
 345     else {
 346         sub_nb A_j(A); A_j.reset(_j);
 347
 348         double result = M[i][_j] * appM(i, A_j);
 349         for( size_t _k = 0; _k < A_j.size(); _k++ )
 350             if( A_j.test(_k) ) {
 351                 sub_nb A_jk(A_j); A_jk.reset(_k);
 352                 result += cors[i][_j][_k] * appM(i,A_jk);
 353             }
 354
 355         return result;
 356     }
 357 }
 358
 359
 360 void MR::sum_subs(size_t j, sub_nb A, double *sum_even, double *sum_odd) {
 361     // j is a variable index
 362     // A is a subset of nb[j]
 363
 364     // calculate sum over all even/odd subsets B of A of _tJ(j,B) appM(j,B)
 365
 366     *sum_even = 0.0;
 367     *sum_odd = 0.0;
 368
 369     sub_nb B(A.size());
 370     do {
 371         if( B.count() % 2 )
 372             *sum_odd += _tJ(j,B) * appM(j,B);
 373         else
 374             *sum_even += _tJ(j,B) * appM(j,B);
 375
 376         // calc next subset B
 377         size_t bit = 0;
 378         for( ; bit < A.size(); bit++ )
 379             if( A.test(bit) ) {
 380                 if( B.test(bit) )
 381                     B.reset(bit);
 382                 else {
 383                     B.set(bit);
 384                     break;
 385                 }
 386             }
 387     } while (!B.none());
 388 }
 389
 390
 391 void MR::solvemcav() {
 392     double sum_even, sum_odd;
 393     double maxdev;
 394     size_t maxruns = 1000;
 395
 396     makekindex();
 397     for(size_t i=0; i<N; i++)
 398         for(size_t _j=0; _j<con[i]; _j++)
 399             M[i][_j]=0.1;
 400
 401     size_t run=0;
 402     do {
 403         maxdev=0.0;
 404         run++;
 405         for(size_t i=0; i<N; i++){ // for all i
 406             for(size_t _j=0; _j<con[i]; _j++){ // for all j in N_i
 407                 size_t _i = kindex[i][_j];
 408                 size_t j = nb[i][_j];
 409                 assert( nb[j][_i] == i );
 410
 411                 double newM = 0.0;
 412                 if( props.updates == Properties::UpdateType::FULL ) {
 413                     // find indices in nb[j] that do not correspond with i
 414                     sub_nb _nbj_min_i(con[j]);
 415                     _nbj_min_i.set();
 416                     _nbj_min_i.reset(kindex[i][_j]);
 417
 418                     // find indices in nb[i] that do not correspond with j
 419                     sub_nb _nbi_min_j(con[i]);
 420                     _nbi_min_j.set();
 421                     _nbi_min_j.reset(_j);
 422
 423                     sum_subs(j, _nbj_min_i, &sum_even, &sum_odd);
 424                     newM = (tanh(theta[j]) * sum_even + sum_odd) / (sum_even + tanh(theta[j]) * sum_odd);
 425
 426                     sum_subs(i, _nbi_min_j, &sum_even, &sum_odd);
 427                     double denom = sum_even + tanh(theta[i]) * sum_odd;
 428                     double numer = 0.0;
 429                     for(size_t _k=0; _k<con[i]; _k++) if(_k != _j) {
 430                         sub_nb _nbi_min_jk(_nbi_min_j);
 431                         _nbi_min_jk.reset(_k);
 432                         sum_subs(i, _nbi_min_jk, &sum_even, &sum_odd);
 433                         numer += tJ[i][_k] * cors[i][_j][_k] * (tanh(theta[i]) * sum_even + sum_odd);
 434                     }
 435                     newM -= numer / denom;
 436                 } else if( props.updates == Properties::UpdateType::LINEAR ) {
 437                     newM = T(j,_i);
 438                     for(size_t _l=0; _l<con[i]; _l++) if( _l != _j )
 439                         newM -= Omega(i,_j,_l) * tJ[i][_l] * cors[i][_j][_l];
 440                     for(size_t _l1=0; _l1<con[j]; _l1++) if( _l1 != _i )
 441                         for( size_t _l2=_l1+1; _l2<con[j]; _l2++) if( _l2 != _i)
 442                             newM += Gamma(j,_i,_l1,_l2) * tJ[j][_l1] * tJ[j][_l2] * cors[j][_l1][_l2];
 443                 }
 444
 445                 double dev = newM - M[i][_j];
 446 //              dev *= 0.02;
 447                 if( fabs(dev) >= maxdev )
 448                     maxdev = fabs(dev);
 449
 450                 newM = M[i][_j] + dev;
 451                 if( fabs(newM) > 1.0 )
 452                     newM = sign(newM);
 453                 M[i][_j] = newM;
 454             }
 455         }
 456     } while((maxdev>props.tol)&&(run<maxruns));
 457
 458     _iters = run;
 459     if( maxdev > _maxdiff )
 460         _maxdiff = maxdev;
 461
 462     if(run==maxruns){
 463         if( props.verbose >= 1 )
 464             cout << "solve_mcav: Convergence not reached (maxdev=" << maxdev << ")..." << endl;
 465     }
 466 }
 467
 468
 469 void MR::solveM() {
 470     for(size_t i=0; i<N; i++) {
 471         if( props.updates == Properties::UpdateType::FULL ) {
 472             // find indices in nb[i]
 473             sub_nb _nbi(con[i]);
 474             _nbi.set();
 475
 476             // calc numerator1 and denominator1
 477             double sum_even, sum_odd;
 478             sum_subs(i, _nbi, &sum_even, &sum_odd);
 479
 480             Mag[i] = (tanh(theta[i]) * sum_even + sum_odd) / (sum_even + tanh(theta[i]) * sum_odd);
 481
 482         } else if( props.updates == Properties::UpdateType::LINEAR ) {
 483             sub_nb empty(con[i]);
 484             Mag[i] = T(i,empty);
 485
 486             for(size_t _l1=0; _l1<con[i]; _l1++)
 487                 for( size_t _l2=_l1+1; _l2<con[i]; _l2++)
 488                     Mag[i] += Gamma(i,_l1,_l2) * tJ[i][_l1] * tJ[i][_l2] * cors[i][_l1][_l2];
 489         }
 490         if(fabs(Mag[i])>1.)
 491             Mag[i] = sign(Mag[i]);
 492     }
 493 }
 494
 495
 496 void MR::init_cor() {
 497     for( size_t i = 0; i < nrVars(); i++ ) {
 498         vector<Factor> pairq;
 499         if( props.inits == Properties::InitType::CLAMPING ) {
 500             BP bpcav(*this, PropertySet()("updates", string("SEQMAX"))("tol", string("1e-9"))("maxiter", string("10000UL"))("verbose", string("0UL"))("logdomain", string("0")));
 501             bpcav.makeCavity( i );
 502             pairq = calcPairBeliefs( bpcav, delta(i), false );
 503         } else if( props.inits == Properties::InitType::EXACT ) {
 504             JTree jtcav(*this, PropertySet()("updates", string("HUGIN"))("verbose", string("0UL")) );
 505             jtcav.makeCavity( i );
 506             pairq = calcPairBeliefs( jtcav, delta(i), false );
 507         }
 508         for( size_t jk = 0; jk < pairq.size(); jk++ ) {
 509             VarSet::const_iterator kit = pairq[jk].vars().begin();
 510             size_t j = findVar( *(kit) );
 511             size_t k = findVar( *(++kit) );
 512             pairq[jk].normalize();
 513             double cor = (pairq[jk][3] - pairq[jk][2] - pairq[jk][1] + pairq[jk][0]) - (pairq[jk][3] + pairq[jk][2] - pairq[jk][1] - pairq[jk][0]) * (pairq[jk][3] - pairq[jk][2] + pairq[jk][1] - pairq[jk][0]);
 514             for( size_t _j = 0; _j < con[i]; _j++ ) if( nb[i][_j] == j )
 515                 for( size_t _k = 0; _k < con[i]; _k++ ) if( nb[i][_k] == k ) {
 516                     cors[i][_j][_k] = cor;
 517                     cors[i][_k][_j] = cor;
 518                 }
 519         }
 520     }
 521 }
 522
 523
 524 string MR::identify() const {
 525     return string(Name) + printProperties();
 526 }
 527
 528
 529 double MR::run() {
 530     if( supported ) {
 531         if( props.verbose >= 1 )
 532             cout << "Starting " << identify() << "...";
 533
 534         double tic = toc();
 535 //        Diffs diffs(nrVars(), 1.0);
 536
 537         M.resize(N);
 538         for(size_t i=0; i<N; i++)
 539           M[i].resize(kmax);
 540
 541         cors.resize(N);
 542         for(size_t i=0; i<N; i++)
 543           cors[i].resize(kmax);
 544         for(size_t i=0; i<N; i++)
 545           for(size_t j=0; j<kmax; j++)
 546             cors[i][j].resize(kmax);
 547
 548         kindex.resize(N);
 549         for(size_t i=0; i<N; i++)
 550           kindex[i].resize(kmax);
 551
 552         if( props.inits == Properties::InitType::RESPPROP ) {
 553             double md = init_cor_resp();
 554             if( md > _maxdiff )
 555                 _maxdiff = md;
 556         } else if( props.inits == Properties::InitType::EXACT )
 557             init_cor(); // FIXME no MaxDiff() calculation
 558         else if( props.inits == Properties::InitType::CLAMPING )
 559             init_cor(); // FIXME no MaxDiff() calculation
 560
 561         solvemcav();
 562
 563         Mag.resize(N);
 564         solveM();
 565
 566         if( props.verbose >= 1 )
 567             cout << Name << " needed " << toc() - tic << " seconds." << endl;
 568
 569         return 0.0;
 570     } else
 571         return 1.0;
 572 }
 573
 574
 575 void MR::makekindex() {
 576     for(size_t i=0; i<N; i++)
 577         for(size_t j=0; j<con[i]; j++) {
 578             size_t ij = nb[i][j];       // ij is the j'th neighbour of spin i
 579             size_t k=0;
 580             while( nb[ij][k] != i )
 581                 k++;
 582             kindex[i][j] = k;   // the j'th neighbour of spin i has spin i as its k'th neighbour
 583         }
 584 }
 585
 586
 587 Factor MR::belief( const Var &n ) const {
 588     if( supported ) {
 589         size_t i = findVar( n );
 590
 591         Real x[2];
 592         x[0] = 0.5 - Mag[i] / 2.0;
 593         x[1] = 0.5 + Mag[i] / 2.0;
 594
 595         return Factor( n, x );
 596     } else
 597         return Factor();
 598 }
 599
 600
 601 vector<Factor> MR::beliefs() const {
 602     vector<Factor> result;
 603     for( size_t i = 0; i < nrVars(); i++ )
 604         result.push_back( belief( var(i) ) );
 605     return result;
 606 }
 607
 608
 609
 610 MR::MR( const FactorGraph &fg, const PropertySet &opts ) : DAIAlgFG(fg), supported(true), _maxdiff(0.0), _iters(0) {
 611     setProperties( opts );
 612
 613     // check whether all vars in fg are binary
 614     // check whether connectivity is <= kmax
 615     for( size_t i = 0; i < fg.nrVars(); i++ )
 616         if( (fg.var(i).states() > 2) || (fg.delta(i).size() > kmax) ) {
 617             supported = false;
 618             break;
 619         }
 620
 621     if( !supported )
 622         return;
 623
 624     // check whether all interactions are pairwise or single
 625     for( size_t I = 0; I < fg.nrFactors(); I++ )
 626         if( fg.factor(I).vars().size() > 2 ) {
 627             supported = false;
 628             break;
 629         }
 630
 631     if( !supported )
 632         return;
 633
 634     // create w and th
 635     size_t Nin = fg.nrVars();
 636
 637     double *w = new double[Nin*Nin];
 638     double *th = new double[Nin];
 639
 640     for( size_t i = 0; i < Nin; i++ ) {
 641         th[i] = 0.0;
 642         for( size_t j = 0; j < Nin; j++ )
 643             w[i*Nin+j] = 0.0;
 644     }
 645
 646     for( size_t I = 0; I < fg.nrFactors(); I++ ) {
 647         const Factor &psi = fg.factor(I);
 648         if( psi.vars().size() == 1 ) {
 649             size_t i = fg.findVar( *(psi.vars().begin()) );
 650             th[i] += 0.5 * log(psi[1] / psi[0]);
 651         } else if( psi.vars().size() == 2 ) {
 652             size_t i = fg.findVar( *(psi.vars().begin()) );
 653             VarSet::const_iterator jit = psi.vars().begin();
 654             size_t j = fg.findVar( *(++jit) );
 655
 656             w[i*Nin+j] += 0.25 * log(psi[3] * psi[0] / (psi[2] * psi[1]));
 657             w[j*Nin+i] += 0.25 * log(psi[3] * psi[0] / (psi[2] * psi[1]));
 658
 659             th[i] += 0.25 * log(psi[3] / psi[2] * psi[1] / psi[0]);
 660             th[j] += 0.25 * log(psi[3] / psi[1] * psi[2] / psi[0]);
 661         }
 662     }
 663
 664     init(Nin, w, th);
 665
 666     delete th;
 667     delete w;
 668 }
 669
 670
 671 } // end of namespace dai