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

Hi, I have submitted it as a bug ticket in : https://svn.boost.org/trac/boost/ticket/10805 Thanks On Tue, Nov 18, 2014 at 4:13 PM, Belcourt, Kenneth wrote:

Hi Pablo,

On Nov 18, 2014, at 8:41 AM, Pablo Madoery 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 #include #include

using namespace std; using namespace boost;

struct vertexInfo {

};

struct edgeInfo { double capacity; double residualCapacity; double flow; adjacency_list_traits::edge_descriptor

rev;

...

edgeInfo() { residualCapacity = 1000; } };

typedef adjacency_list

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"<

-----------------------------------------------------------------------------------------------------------------------------

...

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, CapacityEdgeMap = boost::adj_list_edge_property_map, ResidualCapacityEdgeMap = boost::adj_list_edge_property_map, ReverseEdgeMap = boost::adj_list_edge_property_map, boost::detail::edge_desc_impl&, long unsigned int, edgeInfo, boost::detail::edge_desc_impl edgeInfo::*>, VertexIndexMap = boost::vec_adj_list_vertex_id_map, typename boost::property_traits<CapacityEdgeMap>::value_type = double, typename boost::graph_traits<Graph>::vertex_descriptor = long unsigned int]: Assertion `algo.is_flow()' failed.

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