1.1 --- a/demo/lp_maxflow_demo.cc	Mon Jun 27 15:22:34 2005 +0000
     1.2 +++ b/demo/lp_maxflow_demo.cc	Mon Jun 27 15:25:33 2005 +0000
     1.3 @@ -34,26 +34,34 @@
     1.4    typedef typename G::OutEdgeIt OutEdgeIt;
     1.5    typedef typename G::InEdgeIt InEdgeIt;
     1.6    
     1.7 +  //Define a map on the edges for the variables of the LP problem
     1.8    typename G::template EdgeMap<LpDefault::Col> x(g);
     1.9    lp.addColSet(x);
    1.10    
    1.11 +  //Nonnegativity and capacity constraints
    1.12    for(EdgeIt e(g);e!=INVALID;++e) {
    1.13      lp.colUpperBound(x[e],cap[e]);
    1.14      lp.colLowerBound(x[e],0);
    1.15    }
    1.16  
    1.17 +
    1.18 +  //Flow conservation constraints for the nodes (except for 's' and 't')
    1.19    for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) {
    1.20      LpDefault::Expr ex;
    1.21      for(InEdgeIt  e(g,n);e!=INVALID;++e) ex+=x[e];
    1.22      for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e];
    1.23      lp.addRow(ex==0);
    1.24    }
    1.25 +  
    1.26 +  //Objective function: the flow value entering 't'
    1.27    {
    1.28      LpDefault::Expr ex;
    1.29      for(InEdgeIt  e(g,t);e!=INVALID;++e) ex+=x[e];
    1.30      for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e];
    1.31      lp.setObj(ex);
    1.32    }
    1.33 +
    1.34 +  //Maximization
    1.35    lp.max();
    1.36  
    1.37  #ifdef HAVE_GLPK
    1.38 @@ -61,6 +69,7 @@
    1.39    lp.messageLevel(3);
    1.40  #endif
    1.41  
    1.42 +  //Solve with the underlying solver
    1.43    lp.solve();
    1.44  
    1.45    return lp.primalValue();