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Re: [Boost-users] A question on the preciseness of the double used in MTL. Can anyone with kindness help me?
by fmingu 31 Mar '10

31 Mar '10

I really do not know how to solve it and need help to get through my work. Can anyone with kindness help me? ---------- 转发邮件信息 ---------- 发件人："fmingu <fmingu(a)163.com>" 发送日期：2010-03-29 09:02:29 收件人：boost-users(a)lists.boost.org 主题： Re:Re: [Boost-users] A question on the preciseness of the double used in MTL. Can anyone with kindness help me? 在2010-03-29 08:28:13，"Steven Watanabe" <watanabesj(a)gmail.com> 写道： >AMDG > >fmingu wrote: >> I am using MTL(Matrix Template Library) for Matrix computing in Dev-C++ 4.9.8.0 and updated the gcc version from 3.2 to 4.4.1 by installing tdm-mingw-1.908.0-4.4.1-2 and the boost version is 1.37.0. The system is Windows xp The sample code is : >> >> >> >> #include <boost/numeric/mtl/mtl.hpp> >> >> >> >> #include "boost/random/normal_distribution.hpp" >> >> #include <boost/random.hpp> >> >> #include <boost/random/uniform_real.hpp> >> >> >> >> >> >> int main(int argc, char* argv[]) >> >> { >> >> using namespace mtl; using namespace mtl::matrix; >> >> >> >> const unsigned n= 5; >> >> dense2D<double> A(n, n), B(n, n); >> >> morton_dense<double, doppled_64_row_mask> C(n, n), D(n, n); >> >> >> >> dense2D<double> F(n, n), E(n, n); >> >> hessian_setup(A, 3.0); hessian_setup(B, 1.0); >> >> hessian_setup(C, 2.0); hessian_setup(D, 11.0); >> >> B(1,1)=9.9999; >> >> .......................... >> >> std::cout << "The matrices are: B=\n" << B <<"\n"; >> >> std::cout << "The result is " <<1.0/3.0 <<"\n"; >> >> ……………………. >> >> But the result is shown that B(1,1) is 10, and 1.0/3.0 is 0.33. >> >> How can I get the highest precision of the type double and dense2D<double> for scientific computation? >> >> The same question occurred in random number generation in boost random library. >> > >Use std::setprecision to print more digits. > >In Christ, >Steven Watanabe > I rewrote the program following your advice but std::cout << "The matrices are: B=\n" << std::setprecision(5)<<B<<"\n"; do not show any changes while the code: std::cout << "The result is " << std::setprecision(10)<<1.0/3.0 <<"\n"; worked well. How can I do now? Thanks a lot.

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Boost Graph: iterating over internal vertex property
by Trevor Harmon 31 Mar '10

31 Mar '10

Hi, My graph is defined like this: typedef adjacency_list<vecS, vecS, directedS, Foo*> Graph; The vertex indices can be iterated over like this: typedef property_map<Graph, vertex_index_t>::type IndexMap; IndexMap index = get(vertex_index, g); typedef graph_traits<Graph>::vertex_iterator vertex_iter; std::pair<vertex_iter, vertex_iter> vp; for (vp = vertices(g); vp.first != vp.second; ++vp.first) { std::cout << index[*vp.first] << " "; } (This is straight out of the "Quick Tour" document.) But what if I want to iterate over the Foo pointers in my graph? I suppose one way is this: for (int i = 0; i < num_vertices(g); i++) { Foo *foo = g[i]; } But I assume this wouldn't scale if I were to use listS instead vecS. Also, I'd want to use a proper vertex_iterator anyway, so I can grab all the properties I want in one loop. But how can I access my Foo pointer from the vertex_iterator? I've looked though the docs and sample code but I just can't figure it out. Thanks for any tips, Trevor

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[boost-build] dynamic linking and qt under Mac OS X (10.6)
by Tim Odenthal 30 Mar '10

30 Mar '10

Hi! I'm having problems installing software which is compiling perfectly under windows and (k)ubuntu on a (intel) mac. Having using darwin ; in the user-config.jam and having <link>static as a requirement in the jamroot, everything but the parts relying on qt compile, link and work. BUT: - dynamic linking fails (leaving out the <link>static requirement) - linking to the qt libraries fails ( as on ubuntu, I have " import qt ; \ using qt4 : /usr/local/Trolltech/Qt-4.6.2 ;" in my user-config.jam, obviously with the correct path): the linker complaining about "ld: library not found for -lQtOpenGL_debug" (or the same without _debug for release mode) - there are files for *.a, *.la, *.framework, what is the linker looking for? If I try to use "using gcc ;" not even static linking works, the linker complaining about "ld: unknown option: --start-group". I installed qt from source in the most naive way (without any special options to configure). Can anybody give me some hints what might be wrong - which options I should try or where else I went astray? Thanks a lot in advance Tim P.S.: boost tarball was extracted to /usr/local/boost_1_42_0, I built the libraries we use (system, filesystem, serialization, date_time).

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How to retrieve the bundled property map of a compressed_sparse_row_graph
by 吴焱 30 Mar '10

30 Mar '10

I need to get the bundled property map with a key_type of the vertex_descriptor and a value_type of the bundled vertex property type from a compressed_sparse_row_graph by get(vertex_bundle, g), but it failed. It works when the graph is an adjacency_list. 1 #include <iostream> 2 #include <string> 3 #include <boost/graph/graph_traits.hpp> 4 #ifndef CSR 5 #include <boost/graph/adjacency_list.hpp> 6 #else 7 #include <boost/graph/compressed_sparse_row_graph.hpp> 8 #endif 9 using namespace boost; 10 using namespace std; 11 struct City { 12 string name; 13 int population; 14 int zipcode; 15 explicit City(string const &n = "", int pop = 0, int zip = 0) : name(n), population(pop), zipcode(zip){} 16 }; 17 struct Highway { 18 string name; 19 double miles; 20 int speed_limit; 21 explicit Highway(string const &n = "", double m = 0, int s = 0) : name(n), miles(m), speed_limit(s){} 22 }; 23 #ifndef CSR 24 typedef adjacency_list<listS, vecS, bidirectionalS, City, Highway> Graph; 25 #else 26 typedef compressed_sparse_row_graph<directedS, City, Highway> Graph; 27 #endif 28 int main(int argc, char* argv[]) 29 { 30 City ct[3] = { City("Beijing", 20, 100000), City("Tianjin", 10, 200000), City("Shanghai", 18, 300000) }; 31 Highway hway[2] = { Highway("JJWay", 200, 100), Highway("JHWay", 1300, 120) }; 32 graph_traits<Graph>::vertex_iterator vi, vi_end; 33 #ifndef CSR 34 Graph map; 35 Graph::vertex_descriptor v[3]; 36 v[0] = add_vertex(ct[0], map); 37 v[1] = add_vertex(ct[1], map); 38 v[2] = add_vertex(ct[2], map); 39 add_edge(v[0], v[1], hway[0], map); 40 add_edge(v[0], v[2], hway[1], map); 41 #else 42 typedef pair<size_t, size_t> Edge; 43 Edge edges[2] = { Edge(0, 1), Edge(0,2) }; 44 Graph map(edges_are_unsorted, edges, edges + 2, hway, 3); 45 int i = 0; 46 for (tie(vi, vi_end) = vertices(map); vi != vi_end; ++vi) 47 map[*vi] = ct[i++]; 48 #endif 49 property_map<Graph, vertex_bundle_t>::type index = get(vertex_bundle, map); 50 for (tie(vi, vi_end) = vertices(map); vi != vi_end; ++vi) 51 cout<<index[*vi].name<<" \t"<<index[*vi].population<<" \t"<<index[*vi].zipcode<<endl; 52 property_map<Graph, std::string City::*>::type Names = get(&City::name, map); 53 for (tie(vi, vi_end) = vertices(map); vi != vi_end; ++vi) 54 cout<<Names[*vi]<<endl; 55 } g++ test.cpp is OK but g++ -DCSR test.cpp errors at line 49.

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How to use Boost Log
by Jean-Sebastien Stoezel 30 Mar '10

30 Mar '10

Hello, Well I know Boost log (http://torjo.com/) is not part of boost (yet ?) but I haven't been able to figure it out on my own... So I was hoping somebody here could help me. I've installed Boost using Boost Pro. The install is very easy though it does not install Boost Log. I got Boost Log separately but it does not come with libraries directly linkable with VS2009. How can I generate linkable libraries for Boost Pro, for VS2009? Thanks! Jean

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boost file system, program_option no longer build on HPUX/aCC/1.42
by Avi Bahra 30 Mar '10

30 Mar '10

For 1.42 can no longer build boost on HP-UX. File-system, program-options and serialisation all show a similar problem + bjam --build-dir=./tmpBuildDir toolset=acc stage link=static --with-filesystem variant=debug ...patience... ....... acc.compile.c++ tmpBuildDir/boost/bin.v2/libs/ filesystem/build/acc/debug/link-static/threading-multi/utf8_codecvt_facet.o "./libs/detail/utf8_codecvt_facet.cpp", line 255: error #2014-D: extra text after expected end of preprocessing directive #elif WCHAR_MAX > 0x10000 The actual file <boost_root>/libs/detail/utf8_codecvt_facet.cpp appears to have been changed in boost 1.40 for the function get_cont_octet_out_count_impl FROM: // note the following code will generate on some platforms where // wchar_t is defined as UCS2. The warnings are superfluous as // the specialization is never instantitiated with such compilers. template<> int get_cont_octet_out_count_impl<4>(wchar_t word){ if (word < 0x80) { return 0; } if (word < 0x800) { return 1; } if (word < 0x10000) { return 2; } if (word < 0x200000) { return 3; } if (word < 0x4000000) { return 4; } return 5; } TO: template<> int get_cont_octet_out_count_impl<4>(wchar_t word){ if (word < 0x80) { return 0; } if (word < 0x800) { return 1; } // Note that the following code will generate warnings on some platforms // where wchar_t is defined as UCS2. The warnings are superfluous as the // specialization is never instantitiated with such compilers, but this // can cause problems if warnings are being treated as errors, so we guard // against that. Including <boost/detail/utf8_codecvt_facet.hpp> as we do // should be enough to get WCHAR_MAX defined. #if !defined(WCHAR_MAX) # error WCHAR_MAX not defined! #endif // cope with VC++ 7.1 or earlier having invalid WCHAR_MAX #if defined(_MSC_VER) && _MSC_VER <= 1310 // 7.1 or earlier return 2; #elif WCHAR_MAX > 0x10000 if (word < 0x10000) { return 2; } if (word < 0x200000) { return 3; } if (word < 0x4000000) { return 4; } return 5; #else return 2; #endif } Does any one know of a work around ? Any help appreciated. Best regards, Ta, Avi

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Boost Graph some newbie questions
by Michał Nowotka 30 Mar '10

30 Mar '10

Hello, Although some time ago I used boost graph in some of my projects I found this library too generic for me :) I still have some questions: 1. How to check if my graph is a tree? 2. How to generate random graph? (using generate_random_graph) - I can't find any examples of random graph generation so it should be very very easy and I need the simplest possible example. 3. How to use layout functions like random_graph_layout? - as in the question above I can't find any examples. 4. Can I perform all this actions on graph of type boost::adjacency_matrix<boost::directedS> ? -- Regards Michał Nowotka

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[Thread]: code snippet simulating future
by Boost lzw 30 Mar '10

30 Mar '10

Hi folks, To better understand the "future" concept, I am looking at the following code and have several questions: (1) I got a compiling warning: 'this' : used in base member initializer list. How can I get rid of it? (2) how can I bind class's local data x_ into the new thread? I tried: t_(boost::bind(&future<T>::run, this, x_) ), but it does not work. (3) There seems a race condition in the overloaded function call operator()(). What wrong did I do? BTW: if the future is constructed as ctor using: future(boost::function<T ()> const& f); the code snippet works with minor modification. Thanks in advance, Cheers, Robert ====== code snippet ===== #include <boost/bind.hpp> #include <boost/thread/mutex.hpp> #include <boost/thread/thread.hpp> #include <boost/function.hpp> template<typename T> class future : boost::noncopyable { public: future(boost::function<T (int)> const& f, int); T operator()(); private: int x_; bool joined_; T v_; boost::function<T (int)> const& f_; boost::mutex m_; void run(); boost::thread t_; }; template<typename T> future<T>::future(boost::function<T (int)>const& f, int x) : x_(x), joined_(false), v_(T()), f_(f), t_(boost::bind(&future<T>::run, this) ) { } template<typename T> T future<T>::operator()() { mutex::scoped_lock lock(m_); if (!joined_) { t_.join(); joined_ = true; } return v_; } template<typename T> void future<T>::run() { v_ = f_(x_); }

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[filesystem] exists() throws if no disk in CD-ROM drive (Boost version 1.41)
by PB 30 Mar '10

30 Mar '10

Hello, I was looking to remove a wrapper function I wrote a while ago when I was using Boost 1.35.0. This wrapper caught exceptions from boost::filesystem::exists and returned false: bool PathExists(const boost::filesystem::path& path) { try { return boost::filesystem::exists(path); } catch(const boost::filesystem::filesystem_error&) { return false; } } Now our organisation has upgraded to 1.41.0 I wanted to get rid of the wrapper as I can see that ticket 2725 (https://svn.boost.org/trac/boost/ticket/2725) has been fixed in 1.37.0. A quick test shows that I'm still getting exceptions from boost::filesystem::exists() when referring to a CD-ROM drive without any media in it: #include <iostream> #include <boost/filesystem/operations.hpp> int main() { std::cout << boost::filesystem::exists("d:\\afile.txt") << std::endl; } Could someone take a look at this please? Many thanks, Pete

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Program_option: problems parsing multiple commands with multiple arguments
by Luca Luisa 30 Mar '10

30 Mar '10

Hello, this is my first post in Boost. If this post is not in the right mailing list please let me know, many thanks. I have problems using the "program_options" library while parsing a command line with multiple commands with multiple arguments each. The test.cpp is in attachment. I would like to pars such a command: ./test --firstCommand=arg1 arg2 arg3 --secondCommand=arg1 arg2 arg3 and having as result: ************************ First command detected List of parameters passed: arg1, arg2, arg3 Second command detected List of parameters passed: arg1, arg2, arg3 ************************ But the first command bring the second command as part of its list of arguments with the result: *********************** First command detected List of parameters passed: arg1, arg2, arg3, --secondCommand=arg1, arg2, arg3, ********************** Any hints would be appreciate. Regards, Luca

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