March 2011 - Boost - lists.preview.boost.org

[GSOC] Thoughts about a metaheuristic library
by Murilo Adriano Vasconcelos 29 Mar '11

29 Mar '11

Hi, I'm thinking about proposing a library of genetic algorithms for this GSOC and wondered what the community thinks about it. The main idea is to provide a in extensible set of classes that a user can easily implement a GA without difficulty. /* Individual with double as fitness fuction type * An individual is a possible solution for the problem * In this case, bit_individual can be a class with boost::array<bool> * and some more information like the fitness function type * and an interface for basic things like sorting the population */ typedef bit_individual<double> individual_d; // Fitness function: evaluates a solution double fitness_func(const individual_d& ind) { double value = 0.0; // calc the fitness of ind return value; } // Fitness evaluator fitness_function fitness(fitness_func); // A population is a set of solutions population<individual_d> pop; // We can for example initialize the poulation with // some size passing a random number generator (rng) initialize_random_population(pop, SIZE, rng); // The tournament selector: chooses T_SIZE elements from population // and selects the one with greater fitness tournament_selector<individual_d> selector(T_SIZE); // roullete_selector<individual_d> ... // This specifies the mutation rate of each bit of each individual bit_mutation<individual_d> mutator(RATE); // Crossover in bit_crossover<individual_d> cross; // 1-point crossover // bit_crossover<individual_d> cross(n) : n-point crossover // When the algorithm will stop: in this case, number of generations generation_continuator<individual_d> continuator(MAX_GEN); // can be fitness_continuator<individual_d> cont(val) : continues until the best fitness is less than val // Genetic Algorithm functor ga<individual_d> algo(selector, cross, CROSS_RATE, mutator, fitness, continuator); // Run the GA taking pop as initial population algo(pop); // Gets the best element from the population individual_d best_element = pop.best_element(); // Prints the fitness of the best element std::cout << best_element.fitness() << std::endl; For this basic example, the user only have to choose the parameters (like selector, crossover, continuator, ...) and provide a fitness function with the problem specific rating for an individual. This library can be extended to cover more metaheuristics and be parallelized with Boost.MPI. Ideas about the design and other thinks are also welcome. Regards, -- Murilo Adriano Vasconcelos http://murilo.wordpress.com

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lexical_cast crashing on solaris
by boostman 29 Mar '11

29 Mar '11

Hi Boost Experts Below is the code that is causing crash on solaris: entity::VecObj getData(const message::Message & msg) { entity::VecObj odfs; util::MyString keyStr; keyStr = _T("Test msg"); for(size_t i=2; msg.hasKey(keyStr) ; ++i) { util::MyString mdfAlias = msg.value(keyStr); entity::VecObj ret = storage::byAlias(mdfAlias); if(ret.size()) odfs.push_back(ret[0]); keyStr = _T("Test msg") + util::convert(util::getString(i)) + _T("]"); } if(!odfs.size()) throw util::Exception(util::ERROR_MDFNOTFOUND, util::ERROR_MDFNOTFOUND_STR); return odfs; } template std::string getString(const T & val) { std::string res(""); try { res = boost::lexical_cast(val); } catch(bad_lexical_cast &) { } return res; } Below is the stack trace corresponding to it. ----------------- lwp# 248 / thread# 248 -------------------- fd5c6d10 waitid (0, 4b5d, fa2faf40, 3) fd5b9a34 waitpid (4b5d, 0, 0, 0, 1c800, fd5f3580) + 60 000c76e4 void handleSignal(int) (b, 35d4, fa2fb208, fd5f4604, fd5f3580, 4b5d) + 114 fd5c5924 __sighndlr (b, 0, fa2fb208, c75d0, 0, 0) + c fd5ba868 call_user_handler (b, 0, 12, 0, fc395000, fa2fb208) + 3b8 fd3df5d4 void std::ios::init(std::streambuf *) (fa2fb738, 0, 45, fab18, 3, fd4e30a8) + a8 fd3dfce0 std::ios::basic_ios #Nvariant 1() (fa2fb738, fd4e52b8, 103408, 0, fd4e30a8, 348) + 44 fd467648 std::stringstream::basic_stringstream(int) (fa2fb6c8, c, 1e4, fa2fb738, fd4e800c, fd4e30a8) + 48 fc929ec8 boost::detail::lexical_stream<std::string,unsigned>::lexical_stream #Nvariant 1() (fa2fb6c8, fcb1d710, 0, fdbfff58, fd0ee26c, fd0ee830) + 10 fc929bd0 __type_0 boost::lexical_cast<std::string,unsigned>(__type_1) (fa2fb7f4, 2, fa2fb7fb, fcbcbd88, 57b5040, 0) + 28 fc925844 std::string util::getString(const __type_0&) (fa2fb89c, fa2fb8b8, 3, 4, 4bac880, fd0ee8f8) + 64 fca9cf00 std::vector<boost::shared_ptr<entity::Entity> >operation::getData(const message::Message&) (fa2fb964, 8195784, 1a86c, 4288d10, 4288d10, 4288d10) + 168 I am wondering how can this crash can happen for a very simple case of converting from unsigned to string using lexical cast. Any help would be highly appreciated. Regards Boostman -- View this message in context: http://boost.2283326.n4.nabble.com/lexical-cast-crashing-on-solaris-tp34137… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[Parallel Graph] MPI installation procedure
by Cosimo Calabrese 29 Mar '11

29 Mar '11

Hi to all, I'm searching for a detailed procedure to install MPI (such OpenMPI) under Win32 (WinXP in my case) with Boost, and some sample code to use the parallel graph algorithm. Can someone help me? Thanks, Cosimo Calabrese.

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Help needed for shared_ptr issue on iPad2 (dual core ARM)
by Peter Dimov 28 Mar '11

28 Mar '11

Hi everyone, Ticket #5372: https://svn.boost.org/trac/boost/ticket/5372 says that shared_ptr's ARM spinlock implementation (which uses the swp instruction) doesn't work properly on iPad2 (which has a dual core ARM processor). The sample program in the ticket compares it to a loop using __sync_fetch_and_add, which means that the __sync intrinsics are implemented by the compiler the submitter is using. These didn't work on gcc for ARM when we tested them, but may have been added meanwhile. (I can see some code samples that test for 4.4, but the official docs state that ARM intrinsics are only supported on Linux before 4.6, which was released yesterday.) So, we have two questions; first, why does the swp-based spinlock fail, and second, how can we detect support for __sync intrinsics and use them. Anybody with ARM knowledge and iPad2 development access?

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GSOC LP library for Boost
by Chad Seibert 28 Mar '11

28 Mar '11

Hello, Previously, I mentioned implementing an LP library for Boost. However, there didn't seem to be a consensus on how I should go about it. If we can't agree on a method of attack, then there is no hope for me to get a proposal through the selection committee. So now, I solicit the communities advice on writing a wrapper for lp_solve, an LGPL library that purported to be one of the most stable free LP solvers. Do we care that a dependency is LGPL? I've done my due diligence and there doesn't seem to be a comparable MIT/Boost licensed library. Thanks for your consideration, Chad

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[website] New build script
by Daniel James 28 Mar '11

28 Mar '11

Hi, I've been writing a new script for generating the release notes, the feeds and some other things. I'd like to put it in place on the live site soon, so that I can use it to update the site for the boost build release. It should now be easier for you to regenerate the release notes. You'll need python and quickbook on your path. Then run: python build/build.py update from the root of the beta site (you can actually run the script from anywhere, you just need to get the path to 'build.py' correct). There are some other commands, but they're probably not very interesting. You'll need to commit all the changes this makes. If something goes wrong, just commit the quickbook files, and let me know so that I can investigate. I'll still handle all of this if you wish, but it should be easier for you if you want to. I'll update the instructions on the site soon. Daniel

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Call for Mentors
by Andrew Sutton 28 Mar '11

28 Mar '11

All, If you are planning to or would like to mentor a student project for GSoC this year, please login here http://www.google-melange.com/gsoc/homepage/google/gsoc2011 and a) sign up, update your info from last year etc. b) request to be a mentor for Boost c) or contact me with your linkid and I can invite you. I would have done this sooner, but Google was rolling out a new UI for the web app. It looks a lot nicer, but the timing is not especially good. Andrew

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[context] very brief review
by Phil Endecott 28 Mar '11

28 Mar '11

Dear All, This is a very brief note about the proposed Boost.Context that is not really worthy of being called a "review". My main point is that I am pleased to see this functionality being broken out as a separate library, rather than being hidden as a detail of a higher-level functionality e.g. co-routines. This is something that should be encouraged, and furthermore I think that the weaknesses (e.g. documentation) should be reviewed in the context of the alternative being to hide all of this inside Boost.CoRoutine and not documented at all. I have had a quick look at the ARM assembler implementation. Parameter-passing conventions especially wrt the various FP and vector registers is not something that I know much about. If I were going to use this code somewhere, I would like to see a note in the docs or in the source pointing to the reference documentation that the author used to decide what should and what should not be saved. It seems that the ARM code assembles to only three or four instructions for each function. I would have written that as inline assembler, rather than in a .S file. In my view, after this very brief look, I believe that the library should be accepted. Cheers, Phil.

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re-installing boost openMPI
by luxInteg 28 Mar '11

28 Mar '11

Greetings I am playing with boost on a machine with these:- --amd64 linux, gcc-4.5.2 boost-1_46_1 OpenMPI I have compiled boost-1_46_1. I do not yet have mpi installed and later on after MPI is installed I would like recompile boost with mpi support. I would like to know if there are any problems associated with reinstalling boost over an existing installation sincerely luxInteg

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[phoenix] comma woes
by Steven Watanabe 28 Mar '11

28 Mar '11

AMDG I was going to post a response to Lorenzo's question using phoenix, but I ran into a few issues. The initial version I wrote compiles, but doesn't work. #include <boost/phoenix/core.hpp> #include <boost/phoenix/operator.hpp> #include <iostream> #include <vector> #include <algorithm> int main() { double sum = 0.0; int factor = 10; using namespace boost::phoenix; using namespace boost::phoenix::placeholders; std::vector<double> v(3); v[0] = 1.0; v[1] = 2.0; v[2] = 3.0; std::for_each(v.begin(), v.end(), ( ref(sum) += factor * _1, ref(std::cout) << "Summed: " << ref(sum) << std::endl )); return 0; } This is because the overloaded comma operator is provided by statement.hpp, not operator.hpp as I had erroneously assumed. Can we please make sure that the built-in comma operator can't get silently called? After I added #include <boost/phoenix/statement.hpp>, it still doesn't compile and I have no idea how to make it compile, because it tries to copy std::cout. I'm guessing that the result of the comma operator is being deduced as a non-reference, since the cout part compiles fine by itself. In Christ, Steven Watanabe

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