November 2004 - Boost-users

trouble with large graphs
by Sebastian Weber 17 Nov '04

17 Nov '04

Hi! I am trying to use the BGL to create random graphs with 10^6 nodes and approximetly 10^12 edges. My system is: Debian Sarge with Kernel 2.6.8 on a Pentium M 1.6GHz with 1 Gig of RAM g++-3.4.2 boost 1.32.0 latest draft tarballs I am not using the STL libaries from SGI, but the standard libstdc++6 My first shot with the adjacency_list ate all my main memory. Which isn't really surprising. But adjacency_matrix failed also when I passed 10^5 nodes. Running the program within gdb gives me at least the following error message: 0x080c0fec in boost::detail::get_edge_exists<char> \\ (edge_proxy=@0x73fbdc28) at adjacency_matrix.hpp:84 84 return edge_proxy; The basic program layout is: typedef adjacency_matrix< undirectedS > graph_t; int main(int, char*[]) { // number of vertices const std::size_t vertices = int(1e5); // probability of a connection between two vertices const double pc = 0.3; // yielding number of edges to be distributed randomly const std::size_t edges = int(pc * vertices * (vertices - 1) / 2); std::size_t i = 0; while(i++ < edges) { if ((i % int(1e5)) == 0) cout << "Inserting edge no. " << i << "; completed " \\ << (double(i)/double(edges)) * 100.0 << "% ..." << endl; graph_t::edge_descriptor e; bool inserted = false; do { graph_t::vertex_descriptor a = rand_gen(), b; do { b = rand_gen(); } while (a == b); tie(e, inserted) = add_edge(a, b, g); // if insert fails, then this link already exist -> redo! } while(!inserted); } } Any help would be really appreciated. Thanks in advance! Greetings, Sebastian

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Signals & Slots
by Foster, Gareth 17 Nov '04

17 Nov '04

Hello, I was just reading some mention of bugs in boost::signal, is this implementation in competition with libsigc++? i.e. does it aim to do the same job, but under a different license, or is there perhaps some fundamental design difference between the two? Maybe it's a totally unrelated library (it doesn't look that way, but still ...). Either way, thank you for any information. Regards gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Nat Goodspeed Sent: 17 November 2004 13:39 To: boost-users(a)lists.boost.org Subject: RE: [Boost-users] Signal with return value will crash > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of WangYun > Sent: Tuesday, November 16, 2004 10:03 AM > To: boost-users > Subject: [Boost-users] Signal with return value will crash > > I tried the signals, the code below will crash > > #include <boost/signal.hpp> > int _tmain(int argc, _TCHAR* argv[]) > { > boost::signal<int(int)> _sig; > _sig(10); > > return 0; > } > > but code below works well > > #include <boost/signal.hpp> > int _tmain(int argc, _TCHAR* argv[]) > { > boost::signal<void(int)> _sig; > _sig(10); > > return 0; > } > > The only difference is one has return value, the other doesn't, is this a > bug or by design? [Nat] The difference between a void slot and one with a return value is that in the latter case, the signal needs a combiner to figure out what to do with multiple returns from multiple slots. See: http://www.boost.org/doc/html/ch06s02.html#id2520177 I haven't actually tried your example, but it looks to me as though the default combiner isn't working for you. But then you probably want something other than the default anyway -- unless you don't care about the values returned by your slots -- in which case why not use void slots? _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Dimension-independent multi_array slice creation
by Martin Magnusson 17 Nov '04

17 Nov '04

I'm having problems creating a slice of a multi_array in a dimension-independent manner. Could someone please help? The code posted here gives me the error no match for 'operator[]' in 'rn2t[indices]' Some explanations to the code snippet below: My class is templated over an unsigned int Dim. rn2t is a tensor of rank Dim+2 with real-valued elements. bin_index is of dimension Dim+1, and contains integer indices into a tensor. I want my_slice to be the one-dimensional vector pointed to by bin_index. //////////////////////////////////////////////////////////// // Convenience typedefs for multi-rank arrays: typedef typename boost::multi_array<double, Dim+2> Real_N2_Tensor; typedef boost::array<typename Real_N2_Tensor::index, Dim+2> Real_N2_Tensor_Index; typedef typename boost::multi_array<Positive, Dim+1> Positive_N1_Tensor; typedef boost::array<typename Positive_N1_Tensor::index, Dim+1> Positive_N1_Tensor_Index; //////////////////////////////////////////////////////////// template<int Dim> void My_Class<Dim>::calc( Positive_N1_Tensor_Index bin_index, bool add ) { Real_N2_Tensor rn2t; // populate rn2t... // snip... typedef typename Real_N2_Tensor::index_range Range; typename Real_N2_Tensor::index_gen indices; // Is the following lines the correct way to populate 'indices'? indices[bin_index[0]]; for (int a = 0; a < Dim; ++a) indices[bin_index[a+1]]; indices[Range()]; typename Real_N2_Tensor::array_view<1>::type my_slice = rn2t[indices]; ///// ERROR HERE // snip... } //////////////////////////////////////////////////////////// / martin

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Re: Re: [Boost-users] Re: Re: Signal with return value will crash
by WangYun 17 Nov '04

17 Nov '04

>On Nov 16, 2004, at 10:48 PM, a_hao(a)21cn.com wrote: >> I'm using win2000 pro build 5.00.2195 service pack4, Visual Studio >> 2003 version 7.1.3091, boost v1_31_0. >> And I also tested this using boost v1_32_0, also has this bug. >> >> Before crash, this assert will fail: "Assertion failed: first != last, >> file d:\boost_1_31_0\boost\last_value.hpp, line 23" > >Oh, right! That is by-design, then: when you declare a non-void signal >with the default combiner, it has to get a value from somewhere to >return. When first == last, there is no such value so it asserts. If >you don't want this behavior, you can write your own combiner that gets >a result from somewhere else. > > Doug > Ok, I see, thanks Doug and Nat.

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Re: RE: [Boost-users] Signal with return value will crash
by WangYun 17 Nov '04

17 Nov '04

> >[Nat] The difference between a void slot and one with a return value is >that in the latter case, the signal needs a combiner to figure out what >to do with multiple returns from multiple slots. See: > >http://www.boost.org/doc/html/ch06s02.html#id2520177 > >I haven't actually tried your example, but it looks to me as though the >default combiner isn't working for you. But then you probably want >something other than the default anyway -- unless you don't care about >the values returned by your slots -- in which case why not use void >slots? > But I think the signal doesn't care about whether or not there is any slot connected to it, it just fire the signal and handle the return value if there is any. Why it will crash when there is no slot connected to it. Wang Yun

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Re: Re: Signal with return value will crash
by a_hao＠21cn.com 17 Nov '04

17 Nov '04

>> Hi, >> >> I tried the signals, the code below will crash >> >> #include <boost/signal.hpp> >> int _tmain(int argc, _TCHAR* argv[]) >> { >> boost::signal<int(int)> _sig; >> _sig(10); >> >> return 0; >> } >> >> but code below works well >> >> #include <boost/signal.hpp> >> int _tmain(int argc, _TCHAR* argv[]) >> { >> boost::signal<void(int)> _sig; >> _sig(10); >> >> return 0; >> } >> >> The only difference is one has return value, the other doesn't, is >> this a bug or by design? > >Sounds like a bug... could you give us more information? Compiler, >platform, Boost version, etc. > > Doug > I'm using win2000 pro build 5.00.2195 service pack4, Visual Studio 2003 version 7.1.3091, boost v1_31_0. And I also tested this using boost v1_32_0, also has this bug. Before crash, this assert will fail: "Assertion failed: first != last, file d:\boost_1_31_0\boost\last_value.hpp, line 23" Thanks, Wang Yun

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greg_facet max() macro warning
by Timothy Ritchey 17 Nov '04

17 Nov '04

I have a fresh install of the 1.32 draft release tarball compiled with the intel-win32 environment (I have Intel's C++ version 8.1 installed). I started getting the following warning when I uprgaded the draft tarballs (I'm using intel's 8.1 compiler in Visual Studio .NET): C:\Projects\base\boost\boost/date_time/gregorian/greg_facet.hpp(293): warning #54: too few arguments in macro invocation greg_month::max(), s); I seem to be getting them with both greg_month::max() and greg_weekday::max() I noticed that there appeared to be some kind of guards in constrained_value.hpp (BOOST_PREVENT_MACRO_SUBSTITUTION) that were added in 1.32 compared to my 1.31 install. Any advice on what I could be doing wrong? Cheers, tim

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RE: [Boost-users] Signal with return value will crash
by Nat Goodspeed 17 Nov '04

17 Nov '04

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of WangYun > Sent: Tuesday, November 16, 2004 10:03 AM > To: boost-users > Subject: [Boost-users] Signal with return value will crash > > I tried the signals, the code below will crash > > #include <boost/signal.hpp> > int _tmain(int argc, _TCHAR* argv[]) > { > boost::signal<int(int)> _sig; > _sig(10); > > return 0; > } > > but code below works well > > #include <boost/signal.hpp> > int _tmain(int argc, _TCHAR* argv[]) > { > boost::signal<void(int)> _sig; > _sig(10); > > return 0; > } > > The only difference is one has return value, the other doesn't, is this a > bug or by design? [Nat] The difference between a void slot and one with a return value is that in the latter case, the signal needs a combiner to figure out what to do with multiple returns from multiple slots. See: http://www.boost.org/doc/html/ch06s02.html#id2520177 I haven't actually tried your example, but it looks to me as though the default combiner isn't working for you. But then you probably want something other than the default anyway -- unless you don't care about the values returned by your slots -- in which case why not use void slots?

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posix_time::ptime constructor question
by Stuart Allie 17 Nov '04

17 Nov '04

Hi All, I've noticed a problem when trying to use ptime with, for example, STL containers and algorithms: the lack of a default constructor for ptime means a lot of the STL container methods just dont work. For example: std::vector<ptime> v; v.resize(10); // fails because there is no ptime::ptime() constructor! So, my questions are: 1. Is there an easy way to work around this? 2. What's the reason for the lack of a default c'tor? (Couldn't it just set the object to not_a_date_time?) 3. Am I missing something obvious and in fact the ptime class is perfectly compatible with the STL? Thanks, Stuart Allie

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RE: [Boost-users] RE: Manual in pdf?
by Foster, Gareth 17 Nov '04

17 Nov '04

I suppose I'd better shut up and go and read up on Boostbook then :) I presume all Boost projects will be using this in the future, nice consistent docs, loverly! Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Vladimir Prus Sent: 17 November 2004 12:37 To: boost-users(a)lists.boost.org Subject: [Boost-users] RE: Manual in pdf? Foster, Gareth wrote: > You can make PDF documents in openoffice.org writer</shameless > free-software plug> > > No, seriously, OO.o can import HTML, so you could save the pages locally, > import them into one big OO.o doc (ironic short-hand for document), and > then save that out as PDF, then share it of course so that nobody else has > to spend 20 mins doing it. I'm afraid it's a bit too early for shameless free-software plug :-( OO.o can't generate bookmarks or hyperlinks in PDF, which takes away one half of PDF coolness. Boostbook does it all. - Volodya _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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