Changeset 622:28f58740b6f8 in lemon-main

Timestamp:

04/25/09 18:25:59 (16 years ago)

Author:

Peter Kovacs <kpeter@…>

Branch:

default

Phase:

public

Message:

Support infinite bounds in Circulation + fixes (#270, #266)

• Support infinite capacities.
• Bug fix in upperMap().
• Fixes and improvements in the documentation.

File:

• lemon/circulation.h (modified) (11 diffs)

lemon/circulation.h

@@ -22 +22 @@
 #include <lemon/tolerance.h>
 #include <lemon/elevator.h>
+#include <limits>
 
 ///\ingroup max_flow
@@ -120 +121 @@
 
      The exact formulation of this problem is the following.
-     Let \f$G=(V,A)\f$ be a digraph,
-     \f$lower, upper: A\rightarrow\mathbf{R}^+_0\f$ denote the lower and
-     upper bounds on the arcs, for which \f$0 \leq lower(uv) \leq upper(uv)\f$
+     Let \f$G=(V,A)\f$ be a digraph, \f$lower: A\rightarrow\mathbf{R}\f$
+     \f$upper: A\rightarrow\mathbf{R}\cup\{\infty\}\f$ denote the lower and
+     upper bounds on the arcs, for which \f$lower(uv) \leq upper(uv)\f$
      holds for all \f$uv\in A\f$, and \f$sup: V\rightarrow\mathbf{R}\f$
      denotes the signed supply values of the nodes.
@@ -128 +129 @@
      supply, if \f$sup(u)<0\f$, then \f$u\f$ is a demand node with
      \f$-sup(u)\f$ demand.
-     A feasible circulation is an \f$f: A\rightarrow\mathbf{R}^+_0\f$
+     A feasible circulation is an \f$f: A\rightarrow\mathbf{R}\f$
      solution of the following problem.
 
@@ -151 +152 @@
      the direction of the arcs and taking the negative of the supply values
      (e.g. using \ref ReverseDigraph and \ref NegMap adaptors).
+
+     This algorithm either calculates a feasible circulation, or provides
+     a \ref barrier() "barrier", which prooves that a feasible soultion
+     cannot exist.
 
      Note that this algorithm also provides a feasible solution for the
@@ -338 +343 @@
   private:
 
+    bool checkBoundMaps() {
+      for (ArcIt e(_g);e!=INVALID;++e) {
+        if (_tol.less((*_up)[e], (*_lo)[e])) return false;
+      }
+      return true;
+    }
+
     void createStructures() {
       _node_num = _el = countNodes(_g);
@@ -381 +393 @@
     /// Sets the upper bound (capacity) map.
     /// \return <tt>(*this)</tt>
-    Circulation& upperMap(const LowerMap& map) {
+    Circulation& upperMap(const UpperMap& map) {
       _up = &map;
       return *this;
@@ -468 +480 @@
     void init()
     {
+      LEMON_DEBUG(checkBoundMaps(),
+        "Upper bounds must be greater or equal to the lower bounds");
+
       createStructures();
 
@@ -497 +512 @@
     void greedyInit()
     {
+      LEMON_DEBUG(checkBoundMaps(),
+        "Upper bounds must be greater or equal to the lower bounds");
+
       createStructures();
 
@@ -504 +522 @@
 
       for (ArcIt e(_g);e!=INVALID;++e) {
-        if (!_tol.positive((*_excess)[_g.target(e)] + (*_up)[e])) {
+        if (!_tol.less(-(*_excess)[_g.target(e)], (*_up)[e])) {
           _flow->set(e, (*_up)[e]);
           (*_excess)[_g.target(e)] += (*_up)[e];
           (*_excess)[_g.source(e)] -= (*_up)[e];
-        } else if (_tol.positive((*_excess)[_g.target(e)] + (*_lo)[e])) {
+        } else if (_tol.less(-(*_excess)[_g.target(e)], (*_lo)[e])) {
           _flow->set(e, (*_lo)[e]);
           (*_excess)[_g.target(e)] += (*_lo)[e];
@@ -749 +767 @@
     {
       Flow delta=0;
+      Flow inf_cap = std::numeric_limits<Flow>::has_infinity ?
+        std::numeric_limits<Flow>::infinity() :
+        std::numeric_limits<Flow>::max();
       for(NodeIt n(_g);n!=INVALID;++n)
         if(barrier(n))
@@ -756 +777 @@
           Node s=_g.source(e);
           Node t=_g.target(e);
-          if(barrier(s)&&!barrier(t)) delta+=(*_up)[e];
+          if(barrier(s)&&!barrier(t)) {
+            if (_tol.less(inf_cap - (*_up)[e], delta)) return false;
+            delta+=(*_up)[e];
+          }
           else if(barrier(t)&&!barrier(s)) delta-=(*_lo)[e];
         }