Hello, I am trying to run the metric_tsp_approx.cpp example, but I get an error, I am using the suggested data 3 vertices data, I don't know what I am doing wrong, please help. Vicky. http://www.boost.org/doc/libs/1_58_0/libs/graph/test/metric_tsp_approx.cpp $more graph.txt 1,2 20,4 15,7 I get this error: terminate called after throwing an instance of 'boost::exception_detail::clone_implboost::negative_edge >' what(): The graph may not contain an edge with negative weight. Aborted (core dumped) Its after all the graph is connected: we can parse the given file Opened file 1,2 20,4 15,7 Closed file (1,2) -> (20,4) = 19.105 (1,2) -> (15,7) = 14.8661 (20,4) -> (15,7) = 5.83095 Conected all terminate called after throwing an instance of 'boost::exception_detail::clone_implboost::negative_edge >' what(): The graph may not contain an edge with negative weight. Aborted (core dumped) This is what I get when doing a backtrace: (shortened) (gdb) bt #0 0x00007ffff722bcc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 #1 0x00007ffff722f0d8 in __GI_abort () at abort.c:89 #2 0x00007ffff7b36535 in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #3 0x00007ffff7b346d6 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #4 0x00007ffff7b34703 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #5 0x00007ffff7b34922 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #6 0x00000000004085c8 in boost::throw_exceptionboost::negative_edge (e=...) at /usr/include/boost/throw_exception.hpp:67 #7 0x0000000000408b0f in examine_edge