Re: [Boost-users] [EXTERNAL] [BGL] [push_relabel_max_flow]

Subject: Re: [Boost-users] [EXTERNAL] [BGL] [push_relabel_max_flow]
From: Belcourt, Kenneth (kbelco_at_[hidden])
Date: 2014-11-18 14:13:52

Hi Pablo,

On Nov 18, 2014, at 8:41 AM, Pablo Madoery <madoerypablo_at_[hidden]> wrote:

> Hello, I am having trouble using the push_relabel_max_flow algorithm when i put std::numeric_limits<double>::max() as capacity attribute in some edges.
> is there a maximum value that I can use as capacities. which ?.

I can reproduce this failure with clang on the develop branch.  Can you submit a bug in trac for this issue so it doesn’t get lost?

Thanks.

— Noel Belcourt

> 
> This is the example I am using :
> 
> #include <iostream>
> #include <boost/graph/adjacency_list.hpp>
> #include <boost/graph/push_relabel_max_flow.hpp>
> #include <boost/graph/graphviz.hpp>
> 
> using namespace std;
> using namespace boost;
> 
> struct vertexInfo
> {
> 
> };
> 
> struct edgeInfo
> {
> 	double capacity;
> 	double residualCapacity;
> 	double flow;
> 	adjacency_list_traits<vecS, vecS, bidirectionalS>::edge_descriptor rev;
> 
> 	edgeInfo()
> 	{
> 		residualCapacity = 1000;
> 	}
> };
> 
> typedef adjacency_list<vecS, vecS, bidirectionalS, vertexInfo, edgeInfo> Graph;
> typedef Graph::edge_descriptor edge_d;
> 
> const char* names[] =
> { "SV", "L1", "L2", "L3", "L4", "ET"};
> 
> template<typename Vertex>
> void create_edge(Graph& g, Vertex v0, Vertex v1, double capacity)
> {
> 	//the algorithm requires that for each edge u-v in the graph, the edge v-u also exists
> 	Graph::edge_descriptor ep0 = (add_edge(v0, v1, g)).first;
> 	Graph::edge_descriptor ep1 = (add_edge(v1, v0, g)).first;
> 	g[ep0].capacity = capacity;
> 	g[ep0].rev = ep1;
> 	g[ep1].capacity = 0; // the capacity of v-u needs to be 0
> 	g[ep1].rev = ep0;
> }
> 
> int main()
> {
> 	Graph graph;
> 
> 	Graph::vertex_descriptor SV = add_vertex(graph);
> 	Graph::vertex_descriptor L1 = add_vertex(graph);
> 	Graph::vertex_descriptor L2 = add_vertex(graph);
> 	Graph::vertex_descriptor L3 = add_vertex(graph);
> 	Graph::vertex_descriptor L4 = add_vertex(graph);
> 	Graph::vertex_descriptor ET = add_vertex(graph);
> 
> 
> 	create_edge(graph, SV, L1, std::numeric_limits<double>::max());
> 	create_edge(graph, SV, L2, std::numeric_limits<double>::max());
> 	create_edge(graph, SV, L3, std::numeric_limits<double>::max());
> 	create_edge(graph, SV, L4, std::numeric_limits<double>::max());
> 
> 	create_edge(graph, L3, ET, 1000);
> 
> 	create_edge(graph, L4, L3, 1000);
> 	create_edge(graph, L2, L3, 1000);
> 	create_edge(graph, L1, L2, 1000);
> 
> 	// arcos de vuelta
> 	create_edge(graph, L3, L4, 1000);
> 	create_edge(graph, L3, L2, 1000);
> 	create_edge(graph, L2, L1, 1000);
> 
> 	std::cout << "Max flow: "
> 			<< push_relabel_max_flow(graph, SV, ET, get(&edgeInfo::capacity, graph), get(&edgeInfo::residualCapacity, graph),
> 					get(&edgeInfo::rev, graph), get(boost::vertex_index, graph)) << std::endl;
> 
> 	graph_traits<Graph>::vertex_iterator vi, vi_end;
> 	graph_traits<Graph>::out_edge_iterator ei, ei_end;
> 
> 	cout.precision(20);
> 	for (tie(vi, vi_end) = vertices(graph); vi!= vi_end; ++vi)
> 	{
> 		for (tie(ei, ei_end) = out_edges(*vi, graph); ei != ei_end; ++ei)
> 		{
> 			graph[*ei].flow = graph[*ei].capacity - graph[*ei].residualCapacity;
> 
> 			if (graph[*ei].capacity > 0)
> 			{
> 				std::cout << names[*vi] << " " << names[target(*ei, graph)] << " "
> 						<< (graph[*ei].capacity - graph[*ei].residualCapacity) << "/" << graph[*ei].capacity << std::endl;
> 			}
> 		}
> 	}
> 
> 	cout<<"end"<<endl;
> 	return 0;
> }
> 
> 
> -----------------------------------------------------------------------------------------------------------------------------
> And this is the exception:
> 
> /home/madoery/boost_1_55_0/boost/graph/push_relabel_max_flow.hpp:706: typename boost::property_traits<CapacityEdgeMap>::value_type boost::push_relabel_max_flow(Graph&, typename boost::graph_traits<Graph>::vertex_descriptor, typename boost::graph_traits<Graph>::vertex_descriptor, CapacityEdgeMap, ResidualCapacityEdgeMap, ReverseEdgeMap, VertexIndexMap) [with Graph = boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, vertexInfo, edgeInfo>, CapacityEdgeMap = boost::adj_list_edge_property_map<boost::bidirectional_tag, double, double&, long unsigned int, edgeInfo, double edgeInfo::*>, ResidualCapacityEdgeMap = boost::adj_list_edge_property_map<boost::bidirectional_tag, double, double&, long unsigned int, edgeInfo, double edgeInfo::*>, ReverseEdgeMap = boost::adj_list_edge_property_map<boost::bidirectional_tag, boost::detail::edge_desc_impl<boost::bidirectional_tag, long unsigned int>, boost::detail::edge_desc_impl<boost::bidirectional_tag, long unsigned int>&, long unsigned int, edgeInfo, boost::detail::edge_desc_impl<boost::bidirectional_tag, long unsigned int> edgeInfo::*>, VertexIndexMap = boost::vec_adj_list_vertex_id_map<vertexInfo, long unsigned int>, typename boost::property_traits<CapacityEdgeMap>::value_type = double, typename boost::graph_traits<Graph>::vertex_descriptor = long unsigned int]: Assertion `algo.is_flow()' failed.
> 
> Thank You
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