diff -r f0f15d07bf51 -r 411819b8702c test/max_flow_test.cc
--- a/test/max_flow_test.cc	Fri Mar 23 16:09:06 2018 +0100
+++ b/test/max_flow_test.cc	Fri Mar 23 16:09:27 2018 +0100
@@ -26,6 +26,7 @@
 #include <lemon/concepts/maps.h>
 #include <lemon/lgf_reader.h>
 #include <lemon/elevator.h>
+#include <lemon/tolerance.h>
 
 using namespace lemon;
 
@@ -65,6 +66,37 @@
   "source 1\n"
   "target 8\n";
 
+char test_lgf_float[] =
+  "@nodes\n"
+  "label\n"
+  "0\n"
+  "1\n"
+  "2\n"
+  "3\n"
+  "4\n"
+  "5\n"
+  "6\n"
+  "7\n"
+  "8\n"
+  "9\n"
+  "@arcs\n"
+  "      capacity\n"
+  "0 1 0.1\n"
+  "0 2 0.1\n"
+  "0 3 0.1\n"
+  "1 4 0.1\n"
+  "2 4 0.1\n"
+  "3 4 0.1\n"
+  "4 5 0.3\n"
+  "5 6 0.1\n"
+  "5 7 0.1\n"
+  "5 8 0.1\n"
+  "6 9 0.1\n"
+  "7 9 0.1\n"
+  "8 9 0.1\n"
+  "@attributes\n"
+  "source 0\n"
+  "target 9\n";
 
 // Checks the general interface of a max flow algorithm
 template <typename GR, typename CAP>
@@ -165,8 +197,6 @@
   typedef int Value;
   typedef concepts::Digraph Digraph;
   typedef concepts::ReadMap<Digraph::Arc, Value> CapMap;
-  typedef Elevator<Digraph, Digraph::Node> Elev;
-  typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;
 
   Digraph g;
   Digraph::Node n;
@@ -184,13 +214,13 @@
 
 
 template <typename T>
-T cutValue (const SmartDigraph& g,
-              const SmartDigraph::NodeMap<bool>& cut,
-              const SmartDigraph::ArcMap<T>& cap) {
+T cutValue(const SmartDigraph& g,
+           const SmartDigraph::NodeMap<bool>& cut,
+           const SmartDigraph::ArcMap<T>& cap) {
 
-  T c=0;
-  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
-    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
+  T c = 0;
+  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
+    if (cut[g.source(e)] && !cut[g.target(e)]) c += cap[e];
   }
   return c;
 }
@@ -199,10 +229,11 @@
 bool checkFlow(const SmartDigraph& g,
                const SmartDigraph::ArcMap<T>& flow,
                const SmartDigraph::ArcMap<T>& cap,
-               SmartDigraph::Node s, SmartDigraph::Node t) {
+               SmartDigraph::Node s, SmartDigraph::Node t,
+               const Tolerance<T>& tol) {
 
   for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
-    if (flow[e] < 0 || flow[e] > cap[e]) return false;
+    if (tol.negative(flow[e]) || tol.less(cap[e], flow[e])) return false;
   }
 
   for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
@@ -214,28 +245,29 @@
     for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
       sum -= flow[e];
     }
-    if (sum != 0) return false;
+    if (tol.nonZero(sum)) return false;
   }
   return true;
 }
 
-void initFlowTest()
+void checkInitPreflow()
 {
   DIGRAPH_TYPEDEFS(SmartDigraph);
 
   SmartDigraph g;
-  SmartDigraph::ArcMap<int> cap(g),iflow(g);
-  Node s=g.addNode(); Node t=g.addNode();
-  Node n1=g.addNode(); Node n2=g.addNode();
+  SmartDigraph::ArcMap<int> cap(g), iflow(g);
+  Node s = g.addNode(); Node t = g.addNode();
+  Node n1 = g.addNode(); Node n2 = g.addNode();
   Arc a;
-  a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
-  a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
-  a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
+  a = g.addArc(s, n1); cap[a] = 20; iflow[a] = 20;
+  a = g.addArc(n1, n2); cap[a] = 10; iflow[a] = 0;
+  a = g.addArc(n2, t); cap[a] = 20; iflow[a] = 0;
 
-  Preflow<SmartDigraph> pre(g,cap,s,t);
+  Preflow<SmartDigraph> pre(g, cap, s, t);
   pre.init(iflow);
   pre.startFirstPhase();
-  check(pre.flowValue() == 10, "The incorrect max flow value.");
+
+  check(pre.flowValue() == 10, "Incorrect max flow value.");
   check(pre.minCut(s), "Wrong min cut (Node s).");
   check(pre.minCut(n1), "Wrong min cut (Node n1).");
   check(!pre.minCut(n2), "Wrong min cut (Node n2).");
@@ -243,7 +275,7 @@
 }
 
 template <typename MF, typename SF>
-void checkMaxFlowAlg() {
+void checkMaxFlowAlg(const char *input_lgf,  typename MF::Value expected) {
   typedef SmartDigraph Digraph;
   DIGRAPH_TYPEDEFS(Digraph);
 
@@ -252,35 +284,36 @@
   typedef CapMap FlowMap;
   typedef BoolNodeMap CutMap;
 
+  Tolerance<Value> tol;
+
   Digraph g;
   Node s, t;
   CapMap cap(g);
-  std::istringstream input(test_lgf);
-  DigraphReader<Digraph>(g,input)
+  std::istringstream input(input_lgf);
+  DigraphReader<Digraph>(g, input)
       .arcMap("capacity", cap)
-      .node("source",s)
-      .node("target",t)
+      .node("source", s)
+      .node("target", t)
       .run();
 
   MF max_flow(g, cap, s, t);
   max_flow.run();
 
-  check(checkFlow(g, max_flow.flowMap(), cap, s, t),
+  check(!tol.different(expected, max_flow.flowValue()),
+        "Incorrect max flow value.");
+  check(checkFlow(g, max_flow.flowMap(), cap, s, t, tol),
         "The flow is not feasible.");
 
   CutMap min_cut(g);
   max_flow.minCutMap(min_cut);
   Value min_cut_value = cutValue(g, min_cut, cap);
 
-  check(max_flow.flowValue() == min_cut_value,
-        "The max flow value is not equal to the min cut value.");
+  check(!tol.different(expected, min_cut_value),
+        "Incorrect min cut value.");
 
   FlowMap flow(g);
-  for (ArcIt e(g); e != INVALID; ++e) flow[e] = max_flow.flowMap()[e];
-
-  Value flow_value = max_flow.flowValue();
-
-  for (ArcIt e(g); e != INVALID; ++e) cap[e] = 2 * cap[e];
+  for (ArcIt e(g); e != INVALID; ++e) flow[e] = 13 * max_flow.flowMap()[e];
+  for (ArcIt e(g); e != INVALID; ++e) cap[e] = 17 * cap[e];
   max_flow.init(flow);
 
   SF::startFirstPhase(max_flow);       // start first phase of the algorithm
@@ -289,23 +322,24 @@
   max_flow.minCutMap(min_cut1);
   min_cut_value = cutValue(g, min_cut1, cap);
 
-  check(max_flow.flowValue() == min_cut_value &&
-        min_cut_value == 2 * flow_value,
-        "The max flow value or the min cut value is wrong.");
+  check(!tol.different(17 * expected, max_flow.flowValue()),
+        "Incorrect max flow value.");
+  check(!tol.different(17 * expected, min_cut_value),
+        "Incorrect min cut value.");
 
   SF::startSecondPhase(max_flow);       // start second phase of the algorithm
 
-  check(checkFlow(g, max_flow.flowMap(), cap, s, t),
+  check(checkFlow(g, max_flow.flowMap(), cap, s, t, tol),
         "The flow is not feasible.");
 
   CutMap min_cut2(g);
   max_flow.minCutMap(min_cut2);
   min_cut_value = cutValue(g, min_cut2, cap);
 
-  check(max_flow.flowValue() == min_cut_value &&
-        min_cut_value == 2 * flow_value,
-        "The max flow value or the min cut value was not doubled");
-
+  check(!tol.different(17 * expected, max_flow.flowValue()),
+        "Incorrect max flow value.");
+  check(!tol.different(17 * expected, min_cut_value),
+        "Incorrect min cut value.");
 
   max_flow.flowMap(flow);
 
@@ -324,9 +358,9 @@
 
   CutMap min_cut3(g);
   max_flow.minCutMap(min_cut3);
-  min_cut_value=cutValue(g, min_cut3, cap);
+  min_cut_value = cutValue(g, min_cut3, cap);
 
-  check(max_flow.flowValue() == min_cut_value,
+  check(!tol.different(max_flow.flowValue(), min_cut_value),
         "The max flow value or the min cut value is wrong.");
 }
 
@@ -379,17 +413,28 @@
   // Check Preflow
   typedef Preflow<SmartDigraph, SmartDigraph::ArcMap<int> > PType1;
   typedef Preflow<SmartDigraph, SmartDigraph::ArcMap<float> > PType2;
-  checkMaxFlowAlg<PType1, PreflowStartFunctions<PType1> >();
-  checkMaxFlowAlg<PType2, PreflowStartFunctions<PType2> >();
-  initFlowTest();
+  typedef Preflow<SmartDigraph, SmartDigraph::ArcMap<double> > PType3;
+
+  checkMaxFlowAlg<PType1, PreflowStartFunctions<PType1> >(test_lgf, 13);
+  checkMaxFlowAlg<PType2, PreflowStartFunctions<PType2> >(test_lgf, 13);
+  checkMaxFlowAlg<PType3, PreflowStartFunctions<PType3> >(test_lgf, 13);
+
+  checkMaxFlowAlg<PType2, PreflowStartFunctions<PType2> >(test_lgf_float, 0.3);
+  checkMaxFlowAlg<PType3, PreflowStartFunctions<PType3> >(test_lgf_float, 0.3);
+
+  checkInitPreflow();
 
   // Check EdmondsKarp
   typedef EdmondsKarp<SmartDigraph, SmartDigraph::ArcMap<int> > EKType1;
   typedef EdmondsKarp<SmartDigraph, SmartDigraph::ArcMap<float> > EKType2;
-  checkMaxFlowAlg<EKType1, GeneralStartFunctions<EKType1> >();
-  checkMaxFlowAlg<EKType2, GeneralStartFunctions<EKType2> >();
+  typedef EdmondsKarp<SmartDigraph, SmartDigraph::ArcMap<double> > EKType3;
 
-  initFlowTest();
+  checkMaxFlowAlg<EKType1, GeneralStartFunctions<EKType1> >(test_lgf, 13);
+  checkMaxFlowAlg<EKType2, GeneralStartFunctions<EKType2> >(test_lgf, 13);
+  checkMaxFlowAlg<EKType3, GeneralStartFunctions<EKType3> >(test_lgf, 13);
+
+  checkMaxFlowAlg<EKType2, GeneralStartFunctions<EKType2> >(test_lgf_float, 0.3);
+  checkMaxFlowAlg<EKType3, GeneralStartFunctions<EKType3> >(test_lgf_float, 0.3);
 
   return 0;
 }