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  • typedef declaration syntax

    - by mt_serg
    Some days ago I looked at boost sources and found interesting typedef. There is a code from "boost\detail\none_t.hpp": namespace boost { namespace detail { struct none_helper{}; typedef int none_helper::*none_t ; } // namespace detail } // namespace boost I didn't see syntax like that earlier and can't explain the sense of that. This typedef introduces name "none_t" as pointer to int in boost::detail namespace. What the syntax is? And what difference between "typedef int none_helper::*none_t" and for example "typedef int *none_t" ?

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  • Minimum cost strongly connected digraph

    - by Kazoom
    I have a digraph which is strongly connected (i.e. there is a path from i to j and j to i for each pair of nodes (i, j) in the graph G). I wish to find a strongly connected graph out of this graph such that the sum of all edges is the least. To put it differently, I need to get rid of edges in such a way that after removing them, the graph will still be strongly connected and of least cost for the sum of edges. I think it's an NP hard problem. I'm looking for an optimal solution, not approximation, for a small set of data like 20 nodes. Edit A more general description: Given a grap G(V,E) find a graph G'(V,E') such that if there exists a path from v1 to v2 in G than there also exists a path between v1 and v2 in G' and sum of each ei in E' is the least possible. so its similar to finding a minimum equivalent graph, only here we want to minimize the sum of edge weights rather than sum of edges. Edit: My approach so far: I thought of solving it using TSP with multiple visits, but it is not correct. My goal here is to cover each city but using a minimum cost path. So, it's more like the cover set problem, I guess, but I'm not exactly sure. I'm required to cover each and every city using paths whose total cost is minimum, so visiting already visited paths multiple times does not add to the cost.

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  • Modifying bundled properties from visitor

    - by ravenspoint
    How should I modify the bundled properties of a vertex from inside a visitor? I would like to use the simple method of sub-scripting the graph, but the graph parameter passed into the visitor is const, so compiler disallows changes. I can store a reference to the graph in the visitor, but this seems weird. /** A visitor which identifies vertices as leafs or trees */ class bfs_vis_leaf_finder:public default_bfs_visitor { public: /** Constructor @param[in] total reference to int variable to store total number of leaves @param[in] g reference to graph ( used to modify bundled properties ) */ bfs_vis_leaf_finder( int& total, graph_t& g ) : myTotal( total ), myGraph( g ) { myTotal = 0; } /** Called when the search finds a new vertex If the vertex has no children, it is a leaf and the total leaf count is incremented */ template <typename Vertex, typename Graph> void discover_vertex( Vertex u, Graph& g) { if( out_edges( u, g ).first == out_edges( u, g ).second ) { myTotal++; //g[u].myLevel = s3d::cV::leaf; myGraph[u].myLevel = s3d::cV::leaf; } else { //g[u].myLevel = s3d::cV::tree; myGraph[u].myLevel = s3d::cV::tree; } } int& myTotal; graph_t& myGraph; };

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  • Facebook graph API - OAuth Token

    - by Simon R
    I'm trying to retrieve data using the new graph API, however the token I'm retriving from OAuth doesn't appear to be working. The call I'm making is as follows; $token = file_get_contents('https://graph.facebook.com/oauth/access_token?type=client_cred&client_id=<app_id>&client_secret=<app secret>'); This returns a token with a string length of 41. To give you an example of what is returned I have provided below a sample (converted all numbers to 0, all capital letters to 'A' and small case letters to 'a' access_token=000000000000|AaaAaaAaaAAaAaaaaAaaAa0aaAA. I take this access token and attach it to the call request for data, it doesn't appear to be the correct token as it returns nothing. I make the data call as follows; file_get_contents('https://graph.facebook.com/<my_page's_id>/statuses?access_token=000000000000|AaaAaaAaaAAaAaaaaAaaAa0aaAA.') When I manually retrieve this page directly through the browser I get an 500/Internal Server Error Message. Any assistance would be grately appreciated.

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  • Maximum bipartite graph (1,n) "matching"

    - by Imre Kelényi
    I have a bipartite graph. I am looking for a maximum (1,n) "matching", which means that each vertex from partitation A has n associated vertices from partition B. The following figure shows a maximum (1,3) matching in a graph. Edges selected for the matching are red and unselected edges are black. This differs from the standard bipartite matching problem where each vertex is associate with only one other vertex, which could be called (1,1) matching with this notation. If the matching cardinality (n) is not enforced but is an upper bound (vertices from A can have 0 < x <= n associated vertices from B), then the maximum matching can be found easily by transforming the graph to a flow network and finding the max flow. However, this does not guarantee that the maximum number of vertices from A will have n associated pairs from B.

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  • SOLR - Boost function (bf) to increase score of documents whose date is closest to NOW

    - by Mechanic
    Hi all, I have a solr instance containing documents which have a 'startTime' field ranging from last month to a year from now. I'd like to add a boost query/function to boost the scores of documents whose startTime field is close to the current time. So far I have seen a lot of examples which use rord to add boosts to documents whom are newer but I have never seen an example of something like this. Can anyone tell me how to do it please? Thanks

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  • Posting to an Open Graph page

    - by jpoz
    Hello all, I've got a open graph page with a like button, activity feed, etc. I want to be able to post programmatically. The open graph docs says it's possible via the old stream.publish api. I've got a meta tag pointing to my facebook application, but the stream publish api doesn't seem to be able to post. This is what i'm posting via the api: { message='Hello facebook', target_id='ID via curl 'https://graph.facebook.com/?ids', 'uid'='application_id' } I keep getting: "error_code":101,"error_msg":"Invalid API key" What am I missing? Thanks, JP

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  • 3-clique counting in a graph

    - by Legend
    I am operating on a (not so) large graph having about 380K edges. I wrote a program to count the number of 3-cliques in the graph. A quick example: List of edges: A - B B - C C - A C - D List of cliques: A - B - C A 3-clique is nothing but a triangle in a graph. Currently, I am doing this using PHP+MySQL. As expected, it is not fast enough. Is there a way to do this in pure MySQL? (perhaps a way to insert all 3-cliques into a table?)

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  • Display graph without saving using pydot

    - by user506710
    Hello all I am trying to display a simple graph using pydot. My question is that is there any way to display the graph without writing it to a file as currently I use write function to first draw and then have to use the Image module to show the files. However is there any way that the graph directly gets printed on the screen without being saved ?? Also as an update I would like to ask in this same question that I observe that while the image gets saved very quickly when I use the show command of the Image module it takes noticeable time for the image to be seen .... Also sometimes I get the error that the image could'nt be opened because it was either deleted or saved in unavailable location which is not correct as I am saving it at my Desktop..... Does anyone know what's happening and is there a faster way to get the image loaded..... Thanks a lot....

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  • To find a determinate of Matrix using Boost library in c++

    - by user314097
    Hi, I' am required to convert a MATLAB function into C++, and this requires me to find determinate of a matrix. I was told that use of BOOST library would make my job easier. I went through the documentation of BOOST Library, but couldn't find much info about the same. If anyone could give a template for the above operation, It would be of lot of help and would be greatly appreciated. Thanks Regards

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  • Graph paper like drawing software

    - by Algorist
    Hi, I have a college assignment, where I have to draw diagrams of voronoi, delaunay, minimum spanning tree etc for the college. I want to do that in computer. I searched in google with no luck. Is there any good graph drawing software you are aware of? Thank you Bala

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  • Blank graph for some munin plugins

    - by jack
    I have a munin-master and munin-node installed on same server (Ubuntu 9.10 server). Most pre-installed plugins work well but the following plugins are with blank graph: Memcached bytes used Memcached connections Memcached cache hits and misses Memcached cached items Memcached requests Memcached network traffic MySQL Queries Cache Size I run the following 3 script in terminal and results were ok. /etc/munin/plugins/memcached_bytes /etc/munin/plugins/memcached_counters /etc/munin/plugins/memcached_rates But when I tried the command below after "telnet localhost 4949" fetch memcached_bytes # Unknown service etch memcached_bytes_ # timeout pid 28009 - killing...done Does anyone know the reason?

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  • Puppet master and resources graph

    - by jrottenberg
    Hello ! I've setup rrd reporting + graph on my puppet master, my nodes report as expected and I can see the 'changes' and 'time' graphs, but I miss the 'resources' (html and daily weekly monthly yearly graphs) elements. Note resources.rrd files are there, just puppetmaster does not generate the html and png

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  • Facebook like button for a Facebook feed item

    - by jverdeyen
    Here is what I do: When the admin of a website i'm creating adds a new 'news' item to his website, it directly posts the same item on the Facebook 'fanpage' of the website. This is done by an Facebook app with the permissions to post an item on the Facebook fanpage. So far so good. I'm getting the new post id from the facebook graph. Here is what I want to achieve: I'm adding a 'like' button on the original website, but when this is clicked it should be referenced to the same post item on the facebook page. So if someone likes the news post on the website he should also like the referencing facebook feed post. Which is exactly the same. Can this be done? I've been playing around with the href etc of the like button, without any success. When I hit the like button it likes the url given, but is doesn't recognizes that this is a feed post. Any idea? Thx in advance.

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  • Facebook like button for a Facebook feed item

    - by jverdeyen
    Here is what I do: When the admin of a website i'm creating adds a new 'news' item to his website, it directly posts the same item on the Facebook 'fanpage' of the website. This is done by an Facebook app with the permissions to post an item on the Facebook fanpage. So far so good. I'm getting the new post id from the facebook graph. Here is what I want to achieve: I'm adding a 'like' button on the original website, but when this is clicked it should be referenced to the same post item on the facebook page. So if someone likes the news post on the website he should also like the referencing facebook feed post. Which is exactly the same. Can this be done? I've been playing around with the href etc of the like button, without any success. When I hit the like button it likes the url given, but is doesn't recognizes that this is a feed post. Any idea? Thx in advance.

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  • Partial recalculation of visibility on a 2D uniform grid

    - by Martin Källman
    Problem Imagine that we have a 2D uniform grid of dimensions N x N. For this grid we have also pre-computed a visibility look-up table, e.g. with DDA, which answers the boolean query is cell X visible from cell Y? The look-up table is a complete graph KN of the cells V in the grid, with each edge E being a binary value denoting the visibility between its vertices. Question If any given cell has its visibility modified, is it possible to extract the subset Edelta of edges which must have their visibility recomputed due to the change, so as to avoid a full-on recomputation for the entire grid? (Which is N(N-1) / 2 or N2 depending on the implementation) Update If is not possible to solve thi in closed form, then maintaining a separate mapping of each cell and every cell pair who's line intersects said cell might also be an option. This obviously consumes more memory, but the data is static. The increased memory requirement could be reduced by introducing a hierarchy, subdividing the grid into smaller parts, and by doing so the above mapping can be reused for each sub-grid. This would come at a cost in terms of increased computation relative to the number of subdivisions; also requiring a resumable ray-casting algorithm.

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  • Need theoretical help, how to comprehend an if-else dependency net

    - by macbie
    I am going to face a following issue: I'm writing a program that manages some properties, some of them are general and some are specific. Each property is a pair of key and value, and for example: if it is given a general property and other specific property with exactly the same key and value has been existed before then the general property will swap the specific one in the register. If there are two the same general properties - both will remain in the register. And so on; it is like a net of dependencies. In my case I can handle with it intuitively and foresee all cases, but only because the system is not too vast. What if it would? I have met such problems a few times in many different programs and languages (i.e working with C semaphores) and my question is: How to approach this kind of problem? Is this connected with finite state machine, graph theory or something similar? How to be sure that I have considered the whole system and each possible case? Could you recommend some resources (books, sites) to learn from?

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  • C++ Multithreading on Unix

    - by Roger
    I have two related questions: 1) Are there any good books for multithreading in C++, especially now that C++11 contains multithreading in the standard library? 2) I have the Wrox Programming on Unix book (1000 pages fat red one) and within it, it uses the Unix Thread class. How does this code relate to boost and the C++11 multithreading libraries? Is it better/worse/just specific to Unix etc? Is the performance the same?

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  • Munin Aggregate Graphs from several servers

    - by Sparsh Gupta
    I am using DNS round robin load balancing and have divided my total traffic onto multiple servers. Each server does around 300-400req/second but I am interested in having an aggregate graph telling me the TOTAL of all requests per second served by our architecture. Is there any way I can do this. Right now each graph in Munin comes as a separate graph as they depict things on one server. I am using configuration as follow which doesn't work doesnt work for me, does this configuration got errors? [TRAFFIC.AGGREGATED] update no requests.graph_title nGinx requests requests.graph_vlabel nGinx requests per second requests.draw LINE2 requests.graph_args --base 1000 requests.graph_category nginx requests.label req/sec requests.type DERIVE requests.min 0 requests.graph_order output requests.output.sum \ lb1.visualwebsiteoptimizer.com:nginx_request_lb1.visualwebsiteoptimizer.com_request.request \ lb3.visualwebsiteoptimizer.com:nginx_request_lb2.visualwebsiteoptimizer.com_request.request \ lb3.visualwebsiteoptimizer.com:nginx_request_lb3.visualwebsiteoptimizer.com_request.request

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  • Find version of development library from command line?

    - by mathematician1975
    I installed the c++ boost development libraries using Ubuntu software centre. The problem is that it was quite a long time ago and I cannot remember where they are installed nor what version they were. Is there anything I can do from the command line that will tell me what version(s) I have installed on my system?? I know I can do things like gcc -v to get version of an application but is there a similar thing available for libraries? I am using ubuntu 12.04

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  • undefined reference to `main' collect2: ld returned 1 exit status

    - by sobingt
    I am working on this QT project and i am making test cases for my project. Here is a small test case #include <QApplication> #include <QPalette> #include <QPixmap> #include <QSplashScreen> #include <qthread.h> #define BOOST_TEST_MAIN #include <boost/test/unit_test.hpp> #include <boost/make_shared.hpp> # include <boost/thread.hpp> #include "MainWindow.h" namespace { const std::string dbname = "Project.db"; struct SongFixture { SongFixture(const std::string &fixturePath) { // Create the Master file Master::creator(); // Create/open file std::pair<int, SQLiteDbPtr> result = open( dbname, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0); if (result.first != SQLITE_OK) { throw SQLiteError(result.first, sqlite3_errmsg(result.second.get())); } SQLiteDbPtr &spDb = result.second; // Execute all the SQL from the fixture file execSQLFromFile(spDb, fixturePath); } }; std::auto_ptr<SongFixture> pf; } class I : public QThread { public: static void sleep(unsigned long secs) { QThread::sleep(secs); } }; void free_test_function() { BOOST_CHECK(true ); } test_suite* init_unit_test_suite(int argc, char *argv[]) { // Create a fixture for the peer: // Manage fixture creation manually instead of using // BOOST_FIXTURE_TEST_CASE because the fixture depends on runtime args. std::ostringstream fixturePathSS; fixturePathSS << PROJECT_DIR << "/test/songs_fixture.sql"; std::string fixturePath = fixturePathSS.str(); pf.reset(new SongFixture(fixturePath)); QApplication app(argc, argv); MainWindow window("artists"); window.show(); framework::master_test_suite().add( BOOST_TEST_CASE( &free_test_function )); return app.exec(); } Well i am getting any error /usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crt1.o: In function _start': (.text+0x20): undefined reference tomain' collect2: ld returned 1 exit status pls help me you have a lead..thankz I tired adding #define BOOST_TEST_MAIN then i get ../test/UI/main.cpp: In function ‘boost::unit_test::test_suite* init_unit_test_suite(int, char**)’: ../test/UI/main.cpp:75:31: error: redefinition of ‘boost::unit_test::test_suite* init_unit_test_suite(int, char**)’ /usr/local/include/boost/test/unit_test_suite.hpp:223:1: error: ‘boost::unit_test::test_suite* init_unit_test_suite(int, char**)’ previously defined here Well the program is working in Windows but in Linux the above mention problem is observed

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