# HG changeset patch
# User alpar
# Date 1111776967 0
# Node ID 92ba3e62825d45b9dfd9f53cf399dbccab82d7f8
# Parent  a490938ad0aa8d92a0ba76cd8e549c54143e77a6
Constraints (expressions containing <= or >=) can be passed to addRow()
and setRow()

diff -r a490938ad0aa -r 92ba3e62825d src/work/athos/lp/lin_expr.h
--- a/src/work/athos/lp/lin_expr.h	Fri Mar 25 16:19:03 2005 +0000
+++ b/src/work/athos/lp/lin_expr.h	Fri Mar 25 18:56:07 2005 +0000
@@ -18,10 +18,8 @@
 #define LEMON_LIN_EXPR_H
 
 #include<vector>
-
-
 #include<map>
-
+#include<lemon/utility.h>
 ///\file
 ///\brief Classes to handle linear expressions
 namespace lemon {
@@ -39,6 +37,7 @@
 
     Coeff const_comp;
   public:
+    typedef True IsLinExpression;
     ///\e
     SparseLinExpr() : Base(), const_comp(0) { }
     ///\e
@@ -262,6 +261,50 @@
   ///\relates SparseLinExpr
   ///
   template <class V>
+  SparseLinExpr<V> operator+(const V &v,const typename V::ExprValue &c) {
+    SparseLinExpr<V> tmp(v);
+    tmp.constComp()=c;
+    return tmp;
+  }
+
+  ///\e
+  
+  ///\relates SparseLinExpr
+  ///
+  template <class V>
+  SparseLinExpr<V> operator-(const V &v,const typename V::ExprValue &c) {
+    SparseLinExpr<V> tmp(v);
+    tmp.constComp()=-c;
+    return tmp;
+  }
+
+  ///\e
+  
+  ///\relates SparseLinExpr
+  ///
+  template <class V>
+  SparseLinExpr<V> operator+(const typename V::ExprValue &c,const V &v) {
+    SparseLinExpr<V> tmp(v);
+    tmp.constComp()=c;
+    return tmp;
+  }
+
+  ///\e
+  
+  ///\relates SparseLinExpr
+  ///
+  template <class V>
+  SparseLinExpr<V> operator-(const typename V::ExprValue &c,const V &v) {
+    SparseLinExpr<V> tmp(c);
+    tmp[v]=-1;
+    return tmp;
+  }
+
+  ///\e
+  
+  ///\relates SparseLinExpr
+  ///
+  template <class V>
   SparseLinExpr<V> operator+(const V &v1,const V &v2) {
     SparseLinExpr<V> tmp(v1);
     tmp[v2]+=1;
@@ -302,6 +345,154 @@
   }
 
 
+  //////////////////////////////////////////////////////////////////////
+  /// Constraints
+  //////////////////////////////////////////////////////////////////////
+  
+  template <class E>
+  class LinConstr
+  {
+  public:
+    typedef E Expr;
+    typedef typename E::Var Var;
+    typedef typename E::Coeff Coeff;
+    
+    static const Coeff INF;
+    static const Coeff NaN;
+//     static const Coeff INF=0;
+//     static const Coeff NaN=1;
+
+    Expr expr;
+    Coeff lb,ub;
+    
+    LinConstr() : expr(), lb(NaN), ub(NaN) {}
+    LinConstr(Coeff _lb,const Expr &e,Coeff _ub) :
+      expr(e), lb(_lb), ub(_ub) {}
+    LinConstr(const Expr &e,Coeff _ub) : 
+      expr(e), lb(NaN), ub(_ub) {}
+    LinConstr(Coeff _lb,const Expr &e) :
+      expr(e), lb(_lb), ub(NaN) {}
+  };
+
+  template<class E>
+  const typename LinConstr<E>::Coeff LinConstr<E>::INF=
+    std::numeric_limits<Coeff>::infinity();
+  template<class E>
+  const typename LinConstr<E>::Coeff LinConstr<E>::NaN=
+    std::numeric_limits<Coeff>::quiet_NaN();
+
+  
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator<=(const E &e,const E &f) 
+  {
+    return LinConstr<E>(-LinConstr<E>::INF,e-f,0);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator>=(const E &e,const E &f) 
+  {
+    return LinConstr<E>(-LinConstr<E>::INF,f-e,0);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator==(const E &e,const E &f) 
+  {
+    return LinConstr<E>(0,e-f,0);
+  }
+  
+  //////////////////////////////
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator<=(const E &e,const typename E::Coeff &n) 
+  {
+    return LinConstr<E>(e,n);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator>=(const E &e,const typename E::Coeff &n) 
+  {
+    return LinConstr<E>(n,e);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator==(const E &e,const typename E::Coeff &n) 
+  {
+    return LinConstr<E>(n,e,n);
+  }
+
+  //////////////////////////////
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator<=(const typename E::Coeff &n,const E &e) 
+  {
+    return LinConstr<E>(n,e);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator>=(const typename E::Coeff &n,const E &e) 
+  {
+    return LinConstr<E>(e,n);
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator==(const typename E::Coeff &n,const E &e) 
+  {
+    return LinConstr<E>(n,e,n);
+  }
+
+  //////////////////////////////
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator<=(const typename E::Coeff &n,const LinConstr<E> &c) 
+  {
+    LinConstr<E> tmp(c);
+    if(tmp.lb!=tmp.NaN) throw LogicError();
+    else tmp.lb=n;
+    return tmp;
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator>=(const typename E::Coeff &n,const LinConstr<E> &c) 
+  {
+    LinConstr<E> tmp(c);
+    if(tmp.ub!=tmp.NaN) throw LogicError();
+    else tmp.ub=n;
+    return tmp;
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator<=(const LinConstr<E> &c,const typename E::Coeff &n) 
+  {
+    LinConstr<E> tmp(c);
+    if(tmp.ub!=tmp.NaN) throw LogicError();
+    else tmp.ub=n;
+    return tmp;
+  }
+
+  template<class E>
+  typename enable_if<typename E::IsLinExpression, LinConstr<E> >::type
+  operator>=(const LinConstr<E> &c,const typename E::Coeff &n) 
+  {
+    LinConstr<E> tmp(c);
+    if(tmp.lb!=tmp.NaN) throw LogicError();
+    else tmp.lb=n;
+    return tmp;
+  }
+
+  
+
 } //namespace lemon
 
 #endif //LEMON_LIN_EXPR_H
diff -r a490938ad0aa -r 92ba3e62825d src/work/athos/lp/lp_base.cc
--- a/src/work/athos/lp/lp_base.cc	Fri Mar 25 16:19:03 2005 +0000
+++ b/src/work/athos/lp/lp_base.cc	Fri Mar 25 18:56:07 2005 +0000
@@ -22,6 +22,8 @@
   
   const LpSolverBase::Value
   LpSolverBase::INF = std::numeric_limits<Value>::infinity();
+  const LpSolverBase::Value
+  LpSolverBase::NaN = std::numeric_limits<Value>::quiet_NaN();
 
 
 } //namespace lemon
diff -r a490938ad0aa -r 92ba3e62825d src/work/athos/lp/lp_base.h
--- a/src/work/athos/lp/lp_base.h	Fri Mar 25 16:19:03 2005 +0000
+++ b/src/work/athos/lp/lp_base.h	Fri Mar 25 18:56:07 2005 +0000
@@ -116,6 +116,8 @@
     typedef double Value;
     ///The infinity constant
     static const Value INF;
+    ///The not a number constant
+    static const Value NaN;
     
     ///Refer to a column of the LP.
 
@@ -167,6 +169,8 @@
     
     ///Linear expression
     typedef SparseLinExpr<Col> Expr;
+    ///Linear constraint
+    typedef LinConstr<Expr> Constr;
 
   protected:
     _FixId rows;
@@ -318,6 +322,18 @@
       _setRowUpperBound(rows.floatingId(r.id),u-e.constComp());
     }
 
+    ///Set a row (i.e a constaint) of the LP
+
+    ///\param r is the row to be modified
+    ///\param c is a linear expression (see \ref Constr)
+    ///\bug This is a temportary function. The interface will change to
+    ///a better one.
+    void setRow(Row r, const Constr &c) {
+      Value lb= c.lb==NaN?-INF:lb;
+      Value ub= c.ub==NaN?INF:lb;
+      setRow(r,lb,c.expr,ub);
+    }
+
     ///Add a new row (i.e a new constaint) to the LP
 
     ///\param l is the lower bound (-\ref INF means no bound)
@@ -332,6 +348,18 @@
       return r;
     }
 
+    ///Add a new row (i.e a new constaint) to the LP
+
+    ///\param c is a linear expression (see \ref Constr)
+    ///\return The created row.
+    ///\bug This is a temportary function. The interface will change to
+    ///a better one.
+    Row addRow(const Constr &c) {
+      Row r=addRow();
+      setRow(r,c);
+      return r;
+    }
+
     /// Set the lower bound of a column (i.e a variable)
 
     /// The upper bound of a variable (column) have to be given by an 
diff -r a490938ad0aa -r 92ba3e62825d src/work/athos/lp/lp_test.cc
--- a/src/work/athos/lp/lp_test.cc	Fri Mar 25 16:19:03 2005 +0000
+++ b/src/work/athos/lp/lp_test.cc	Fri Mar 25 18:56:07 2005 +0000
@@ -1,5 +1,6 @@
 #include"lp_solver_skeleton.h"
 #include"lp_glpk.h"
+#include<lemon/list_graph.h>
 
 using namespace lemon;
 
@@ -36,9 +37,52 @@
   lp.addRow(LP::INF,3.0*(x[1]+x[2]/2)-x[3],23);
   lp.addRow(LP::INF,3.0*(p1+p2*2-5*p3+12-p4/3)+2*p4-4,23);
   lp.addRow(LP::INF,3.0*(x[1]+x[2]*2-5*x[3]+12-x[4]/3)+2*x[4]-4,23);
+
+  lp.addRow(x[1]+x[3]<=x[5]-3);
+  lp.addRow(-7<=x[1]+x[3]-12<=3);
 }
 
 
+template<class G,class C>
+double maxFlow(const G &g,const C &cap,typename G::Node s,typename G::Node t)
+{
+  LpGlpk lp;
+  
+  typedef G Graph;
+  typedef typename G::Node Node;
+  typedef typename G::NodeIt NodeIt;
+  typedef typename G::Edge Edge;
+  typedef typename G::EdgeIt EdgeIt;
+  typedef typename G::OutEdgeIt OutEdgeIt;
+  typedef typename G::InEdgeIt InEdgeIt;
+  
+  typename G::EdgeMap<LpGlpk::Col> x(g);
+  // lp.addColSet(x);
+  for(EdgeIt e(g);e!=INVALID;++e) x[e]=lp.addCol();
+  
+  for(EdgeIt e(g);e!=INVALID;++e) {
+    lp.setColUpperBound(x[e],cap[e]);
+    lp.setColLowerBound(x[e],0);
+  }
+
+  for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) {
+    LpGlpk::Expr ex;
+    for(InEdgeIt  e(g,n);e!=INVALID;++e) ex+=x[e];
+    for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e];
+    lp.addRow(0,ex,0);
+  }
+  {
+    LpGlpk::Expr ex;
+    for(InEdgeIt  e(g,t);e!=INVALID;++e) ex+=x[e];
+    for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e];
+    lp.setObj(ex);
+  }
+
+  lp.solve();
+
+  return 0;
+}
+
 int main() 
 {
   LpSolverSkeleton lp_skel;
@@ -46,4 +90,10 @@
 
   lpTest(lp_skel);
   lpTest(lp_glpk);
+
+  ListGraph g;
+  ListGraph::EdgeMap<double> cap(g);
+  
+  maxFlow(g,cap,ListGraph::NodeIt(g),ListGraph::NodeIt(g));
+
 }