April 2006 - Boost-users - lists.preview.boost.org

boost::numeric::ublas : matrix comparsion.
by chun ping wang 19 Apr '06

19 Apr '06

I went through the matrix_expression library and realize there is no way of comparing matrix...like say i want to compare ith row together, how would i do that.. (considering i want to write a generic implementation) of matrix comparison Are there any out there?

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[Boost Threads] Setting thread stack size...
by Matt Amato 19 Apr '06

19 Apr '06

I have a Windows application that has some very data intensive threads that require much more than the default 2 MB allocated to them. There doesn't seem to be a way to do this via boost threads (which I already make use of throughtout my app). Is there any way to do this with the current release, or will I have to use beginthreadex directly for these threads. Thanks, Matt

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[serialization] Build error: 1.33.1, vc-8_0 toolset, Windows XP
by Rush Manbert 18 Apr '06

18 Apr '06

Hi, I am having problems building Boost 1.33.1 under Windows XP for the vc-8_0 toolset. My problems seem to come from a bug in the build of the serialization library. The attached zip file contains information from 2 builds. One of them succeeds and the other fails. The difference between them is that the failed build includes "--layout=system" on the bjam command line, while the successful build does not. In both cases, the build is run by a script that makes sure the build location and the installation location are cleaned up before the build starts. In the zip file are the following files: * failedBoostBuild.log contains all of the output generated by bjam for the failed build. * failedConsoleTranscript.txt is the console output from the build script. It shows the bjam command line for the failed build. * failedInstalledLibList.txt is a "dir" listing of the library installation directory, after the failed build completed. * goodBoostBuild.log, goodConsoleTranscript.txt, and goodInstalledLibList.txt are the equivalents to the above for the successful build. I believe that there is an error shown in failedBoostBuild.log at line 3000. The line says: "LINK : fatal error LNK1104: cannot open file 'boost_serialization-vc80-mt-gd-1_33_1.lib'" and I believe that the error is that the library file name includes the toolset name and the Boost version number. Since I specified --layout=system, neither of these are included in the generated library names. There is a similar error at line 3058. If you compare the failedInstalledLibList.txt and goodInstalledLibList.txt, you can see that none of the boost_wserialization libraries are present in the failed case. I am guessing that they represent the four failed targets reported by bjam at the end of the build. I want to use the --layout=system naming conventions and do internal releases of the Boost libraries to our development environment. I have already done this successfully under Mac OSX, and I expected it to work the same way under Windows. If my conclusion that there is a build bug is correct, is there some workaround possible to make the build succeed? (I looked at the serialization jamfile and came away unenlightened. :-) Is there some other explanation? Thanks, Rush

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property map: does a given key exist?
by Irek Szczesniak 18 Apr '06

18 Apr '06

In nutshell: how can I check whether a property map has some given key? The exact problem is as follows. I have graph edges with the property "lambdas" of positive integers, but its the exact meaning is not important here. With the read_graphviz function I am loading graph files which look like this: graph { a; b; c; c -- a [distance="100"]; a -- b [lambdas="8"]; } After I load the file I want to examine which edges have the "lambdas" property, but I don't know how to do this. If I request the property value with the "get" function, I get some random value. My program is at the bottom of this email. The program prints the edge and the value of the "lambdas" property. I get this: (2,0): 33489268 (0,1): 8 The first line is bad: the edge (2,0), i.e. c -- a in my graphviz file, has the reported value of 33489268. The second line is OK. Thanks for reading. Best, Irek ********************************************************************* #include <boost/graph/adjacency_list.hpp> #include <boost/graph/depth_first_search.hpp> #include <boost/graph/iteration_macros.hpp> #include <boost/graph/graphviz.hpp> using namespace boost; typedef boost::adjacency_list<vecS, vecS, undirectedS, property<vertex_name_t, std::string>, property<edge_weight_t, double, property<edge_weight2_t, int> >, no_property > Graph; int main() { Graph g; dynamic_properties dp; dp.property("node_id", get(vertex_name, g)); dp.property("distance", get(edge_weight, g)); dp.property("lambdas", get(edge_weight2, g)); read_graphviz(std::cin, g, dp); typedef boost::property_map<Graph, edge_weight2_t>::type lambdas_t; lambdas_t weight2_map = get(edge_weight2, g); BGL_FORALL_EDGES(e, g, Graph) // Before printing this out I would like to make sure that an edge // has this property. std::cout << e << ": " << get(weight2_map, e) << std::endl; }

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[plugin] run arbitrary function in library / query contained objects
by Tim Blechmann 18 Apr '06

18 Apr '06

hi all, i'm currently trying to incorporate the boost.plugin library from the boost-sandbox cvs into my program. i need to compile one or more plugins into one shared library and i need a possibility to call a certain function in the library to tell me the names of the contained plugins and give me some more information about the plugin. is there a possibility to run an arbitrary function inside the library, using the dll or plugin_factory? the only workaround i was thinking about is using a dummy plugin class, that's providing virtual functions returning information about the library ... any other hints? or is there any way to get the names of the contained plugins of a certain base class? thanks in advance ... tim -- TimBlechmann(a)gmx.de ICQ: 96771783 http://www.mokabar.tk Nothing exists until or unless it is observed. An artist is making something exist by observing it. And his hope for other people is that they will also make it exist by observing it. I call it 'creative observation.' Creative viewing. William S. Burroughs

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how to install boost in a different directory
by yinglcs2＠yahoo.com 18 Apr '06

18 Apr '06

Hi, How can I install boost in a different directory? I try this command: bjam "-sTOOLS=gcc --prefix=/home/yinglcs/boost" install But it gives me error message saying some *.jam file is not found. Thank you for any help. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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program_options: how to retrieve positional options
by Dean Sturtevant 18 Apr '06

18 Apr '06

Let's say one has defined the following: boost::program_options::positional_options_description pdesc; pdesc.add("generic_name", -1); Then included it in the parse: boost::program_options::variables_map options_map; boost::program_options::basic_parsed_options<char> options = boost::program_options::basic_command_line_parser<char>(argc, argv). positional(pdesc).run(); po::store(options, options_map); po::notify(options_map); How does one retrieve the positional options? - Dean

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Boost website failed?
by James Hughes 18 Apr '06

18 Apr '06

I'm trying to look at the Boost documentation - but the website appears to be dead, so I cannot use the bit I want as I have no idea how! Is it possible to download a PDF of all the Boost docs for when this situation arises so I can keep working? James

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Re: [Boost-users] [multi_index] Sorting object based on some specified criteria!!
by Patel Priyank-PPATEL1 18 Apr '06

18 Apr '06

Hi Joaquin, Thanks for all your replies. Let me read carefully the link you sent out. I will write you back in case of any more questions. Thanks for this great library, it is really helpful. Thanks again, Priyank -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Joaquín Mª López Muñoz Sent: Tuesday, April 18, 2006 2:21 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [multi_index] Sorting object based on some specified criteria!! Patel Priyank-PPATEL1 ha escrito: > Hi Joaquin, > > First of all thanks for your time and response. I have it working as follows, but seems I have to recalculate iterators if in case I later on modify group associated with that access point. Is there any way that iterators will know automatically update when I update access point in future to some other group? > Let me know if you have come across that one. I am going to look in your code in detail and get back to you in case of any questions. Hello Priyank, there's an issue in your code: > // change paging group from access point 4 > a4->pg(2); This is incorrect and can lead to hard-to-detect failures later on during the execution of the program: basically, you're changing an element key "under the table", that is, without the multi-index container having a chance to notice, which directly breaks the internal invariants the container relies on. Under usual conditions it is difficult to change a key in such a way, because the elements of a multi-index container are treated as const, but here you can easily get by because it is pointers that you are storing. The proper way to modify an element is by using replace, modify of modify_key, as explained in http://boost.org/libs/multi_index/doc/tutorial.html#ord_updating In your case, instead of what you've got you could write the following: // get an iterator to a4. You could also have stored those iterators in the // first place when inserting the elements. Access_Points::iterator it=pool.find(4); // change paging group from access point 4 pool.modify(it,boost::bind(&Access_point::pg,_1,2)); By using modify(), the multi-index container is on control of the updating operation, and will rearrange a4 according to its new paging group. > // NEED TO RECALCULATE ITERATORS > boost::tuples::tie(pg0, pg1) = get<paging_group> > (pool).equal_range(1); As for your original question, yes, you've got to recalculate these iterators in the general case, as elements might have been moved around, inserted or deleted: for instance, if the element originally pointed to by pg0 had been deleted, pg0 would not even be valid after that. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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ptr_container: splice function in ptr_list
by Detlef Mages 18 Apr '06

18 Apr '06

Hi there, I am using a ptr_list as a (huge) container where I can store objects (different types of a single interface). I am using a ptr_list as I need to store iterators to elements that do not invalidate when reordering the structure. Though a standard function of the STL list is missing: "splice". I know, I can mimic "splice" by "transfer", though I think that this results in a runtime complexity of O(N) whereas "splice" would be O(1). Is there a way to add splice to ptr_list? Or will there be problems I haven't thought of? If you give me some hint I could take a shot on this functionality. Detlef

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