November 2013 - Boost-users

[Math] BOOST_FPU_EXCEPTION_GUARD on Linux
by David Roberts 13 Nov '13

13 Nov '13

Hello, I have a program that makes considerable use of the gamma distribution from Boost.Math. Profiling with OProfile has shown that, on Linux, this program spends about 20% of its runtime calling the functions fesetexceptflag() and feclearexcept(). The code responsible for calling these is in the BOOST_FPU_EXCEPTION_GUARD macro which is defined in boost/math/tools/config.hpp. I have looked back through the source history to see when and why this macro was added, and it was in changeset 3186 from September 2006 with the comment "More linux fixes: finally got AMD64 machines to behave correctly" (see https://svn.boost.org/trac/boost/changeset/3186) In Boost 1.54 the conditions under which the guard macro is defined have been refined since it was originally added, but the guard class itself remains the same as in 2006. Given the performance penalty I am suffering as a result of constantly clearing and reseting the floating point exception flags, I have a couple of questions about this functionality: 1) Can anyone provide a specific test case that did not work without the BOOST_FPU_EXCEPTION_GUARD functionality but was fixed by its addition? It would be very useful to have such a test case because then I can check if this is still a problem on recent versions of Linux. 2) The commit comment for changeset 3186 refers to AMD64. Does this mean the original problem only occurred on AMD CPUs, or does this refer to the architecture, and hence it affected both Intel and AMD CPUs? Many thanks, David Roberts

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[Graph] Static allocation of nodes and edges
by Sensei 13 Nov '13

13 Nov '13

Dear all, I need to optimize my code with regards to both memory and time. The problem is simple: pre-allocating the adjacency matrix. The graph may have a huge number of nodes N, but the number of edges K per node is limited. While N can be in the order of one hundred million, K is at most 10. The graph will be directed, so no symmetry is needed. Do you know if I can pre-allocate such an adjacency matrix? If not, I suppose I must use an adjacency list in order to minimize memory consumption, am I right? Thanks!

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Help with lockfree queue
by TYSON Kieran 13 Nov '13

13 Nov '13

[@@ OPEN @@] Hello, I am using a global lockfree queue to transfer a message from different threads. The program compiles and runs without fault up until the program exits and the queues destructor is called. An unhandled exception is thrown on the destruction of the queue. Below is the code used to set up the queue. #define B1_OUTPUT_LENGTH_PER_CHANNEL (32000) #define B2_OUTPUT_LENGTH_PER_CHANNEL (32000) #define B3_OUTPUT_LENGTH_PER_CHANNEL (64000) #define NB_CHANNELS (8) typedef struct s_OutputMsg { float dataB1[(int)B1_OUTPUT_LENGTH_PER_CHANNEL*NB_CHANNELS]; float dataB2[(int)B2_OUTPUT_LENGTH_PER_CHANNEL*NB_CHANNELS]; float dataB3[(int)B3_OUTPUT_LENGTH_PER_CHANNEL*NB_CHANNELS]; int dataLength; } OutputMsg; boost::lockfree::queue<OutputMsg, boost::lockfree::fixed_sized<true>> dataMsgQueue(100); My first thoughts are that there are limitations on the size of the message because I have used simple integer queues in the past with no problem. Are there size limitations on the message of a lockfree queue? Thanks, Kieran This message contains OPEN information that is not sensitive and can be freely accessed by people both inside and outside of the Thales Group This email was classified by Tyson, Kieran on Wednesday, 13 November 2013 10:58:41 AM ------------------------------------------------------------------------- DISCLAIMER: This e-mail transmission and any documents, files and previous e-mail messages attached to it are private and confidential. They may contain proprietary or copyright material or information that is subject to legal professional privilege. They are for the use of the intended recipient only. Any unauthorised viewing, use, disclosure, copying, alteration, storage or distribution of, or reliance on, this message is strictly prohibited. No part may be reproduced, adapted or transmitted without the written permission of the owner. If you have received this transmission in error, or are not an authorised recipient, please immediately notify the sender by return email, delete this message and all copies from your e-mail system, and destroy any printed copies. Receipt by anyone other than the intended recipient should not be deemed a waiver of any privilege or protection. Thales Australia does not warrant or represent that this e-mail or any documents, files and previous e-mail messages attached are error or virus free. -------------------------------------------------------------------------

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How to convert cmyk jpg file to rgb jpg file with BOOST.GIL?
by Guangchao Wang 13 Nov '13

13 Nov '13

I used following code: rgb8_image_t rgb8Img; jpeg_read_and_convert_image("CMYK.jpg", rgb8Img); //CMYK.jpg is CMYK image jpeg_write_view("RGB.jpg", const_view(rgb8Img)); to convert CMYK image to RGB image. The saved RGB.jpg is not correct. Could you give me some suggestion? Thanks.

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[Locale] Getting correct system locale under Mac OS X
by Orhun Birsoy 11 Nov '13

11 Nov '13

I am using boost 1.55.0.rc2. I am running 10.8.5 and when I select "Norway (Norwegian Bokmal)" (nb_NO) as the region, LANG env. variable is undefined, making boost::locale::generator("") to generate a "C" locale. I can of-course get the locale identifier from NSLocale (or CFLocale) and initialize the boost::locale::generator with "nb_NO" which seems to be working, but with Mavericks things got even more interesting. It looks like, in 10.9 you can mix and match language with a country anyway you like i.e. I can select "Norway" as my region and "English" as my language and again LANG is empty but NSLocale returns "en_NO". But this time when I use boost::locale::generator("en_NO"), boost::locale::as::number uses "." (dot) as decimal separator, although NSLocale reports "," (comma). 1. Can boost::locale handle such combinations (en_NO, en_TR, etc)? (I am using ICU backend, others are explicitly turned off). a. for number formatting? b. for messages formatting (translations)? which mo will it pick for en_TR ? 2. How can I 'customize' locale generated by boost::locale to reflect the changes user might do in system locale settings (i.e. select en_US but change the decimal symbol)? Thanks. -- Orhun Birsoy

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Thanks to everyone for all the work on 1.55.0
by Marshall Clow 11 Nov '13

11 Nov '13

I just wanted to take off my "release manager" hat and say, personally, thank you to all the people who tried out the RCs/Betas/etc, reported bugs, and suggested fixes. You were all a big help in making the release. -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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Boost 1.55.0 released!
by Marshall Clow 11 Nov '13

11 Nov '13

Release 1.55.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains one new library and numerous enhancements and bug fixes for existing libraries. === New Libraries === • Predef: This library defines a set of compiler, architecture, operating system, library, and other version numbers from the information it can gather of C, C++, Objective C, and Objective C++ predefined macros or those defined in generally available headers, from Rene Rivera. === Known bugs with Visual Studio 2013/Visual C++ 12 === Visual Studio 2013 was released quite late in the release process, so there exist several unresolved issues. These include: • Serialization can't compile because of a missing include. • Using has_member_function_callable_with from Boost.Container's allocator_traits causes a compile error (#9332). • For several libraries overloads with intializer lists are incorrectly reported as ambiguous. This is a Visual C++ bug and it isn't clear if there's a good workaround. • In libraries such as Unordered and MultiIndex, calling overloaded functions with initializer lists can result in a compile error, with Visual C++ claiming that the overloads are ambiguous. This is a Visual C++ bug and it isn't clear if there's a good workaround. This won't affect code that doesn't use initializer lists, or uses an initializer list that doesn't require an implicit conversion (i.e. an initializer list of the container's exact value type). • Thread: ex_scoped_thread compile fails (#9333). For details, including download links, see http://www.boost.org/users/news/version_1.55.0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.55.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Vladimir Prus Rene Rivera Marshall Clow Eric Niebler Daniel James Beman Dawes

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[Polygon] attaching data to polygon boundary segments
by Andreas Buhr 10 Nov '13

10 Nov '13

Dear Boost community, I would like to process 2D geometry for a finite element solver using boost.polygon. I programmed it, it's working fine. I use the polygon_data and polygon_set_data types from boost.polygon. Now I would like to attach information to the boundary segments. Then I'd like to do boolean operations. At the end I would like to have the boundary information merged. Is this possible with boost.polygon? A attached a little drawing of what behavior I would like to achieve, colors code the boundary markers. thanks a lot in advance, Best regards, Andreas

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[BGL] how to use write_graphviz_dp with graph bundle properties
by Pablo Madoery 10 Nov '13

10 Nov '13

Hello. I know how to use write_graphviz_dp with vertices and edges bundle properties but i can't figure out how to print the graph_bundle property of a graph. i have the following code where the line with the error is commented: #include <boost/graph/properties.hpp> #include <boost/graph/graphviz.hpp> #include <boost/graph/adjacency_list.hpp> using namespace boost; using namespace std; struct VertexInfo { int id; }; struct EdgeInfo { int weight; }; struct GraphInfo { int duration; }; typedef adjacency_list<vecS, vecS, undirectedS, VertexInfo, EdgeInfo, GraphInfo> Graph; void printGraph(Graph graph, string file) { ofstream ofs(file.c_str()); dynamic_properties dp; dp.property("node_id", get(vertex_index, graph)); dp.property("label", get(&EdgeInfo::weight, graph)); ///dp.property("label", get(&graph[graph_bundle].duration)); ->error write_graphviz_dp(ofs, graph, dp); } int main() { Graph graph; Graph::vertex_descriptor a = add_vertex(graph); Graph::vertex_descriptor b = add_vertex(graph); Graph::vertex_descriptor c = add_vertex(graph); Graph::vertex_descriptor d = add_vertex(graph); Graph::edge_descriptor e1 = (add_edge(a, b, graph)).first; Graph::edge_descriptor e2 = (add_edge(b, c, graph)).first; Graph::edge_descriptor e3 = (add_edge(c, d, graph)).first; Graph::edge_descriptor e4 = (add_edge(d, a, graph)).first; graph[e1].weight = 1.1; graph[e2].weight = 1.5; graph[e3].weight = 5.2; graph[e4].weight = 1.2; graph[graph_bundle].duration = 10; printGraph(graph, "graph.dot"); }

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[Boost.Python] Exposing protected virtual member functions
by Vitaly Budovski 09 Nov '13

09 Nov '13

Hi, I'd like to expose some protected virtual member functions to Python, but I've been unable to find a practical way to do so. I've created a wrapper making the protected functions public, but have not been able to make further progress due to either compile errors or Python runtime exceptions. Is there something I've overlooked in the documentation? Please see code below. Thanks, Vitaly #include <boost/python.hpp> #include <string> using namespace boost::python; class base { //protected: public: virtual std::string f() { return "base::f"; } public: virtual std::string g() = 0; }; class derived: public base { public: std::string g() { return "derived::g"; } }; struct base_wrapper: base, wrapper<base> { std::string f() { if(override f = this->get_override("f")) { return f(); } return base::f(); } std::string default_f() { return base::f(); } std::string g() { return this->get_override("g")(); } }; BOOST_PYTHON_MODULE(protected) { class_<base_wrapper, boost::noncopyable>("base") .def("f", &base::f, &base_wrapper::default_f) .def("g", pure_virtual(&base_wrapper::g)) ; class_<derived, bases<base>, boost::noncopyable>("derived") .def("g", &derived::g) ; }

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