January 2007 - Boost-users - lists.preview.boost.org

shmem map tutorial
by Jan Stetka 31 Jan '07

31 Jan '07

I've put together a tutorial on how to use interprocess map. Its at http://myweb.tiscali.co.uk/janstetka/interprocess_map.html Perhaps there could be a link from the interprocesses documentation if it goes down well. Thanks PS:I tried to use the wiki but the syntax is a bit too difficult for me especially formating code so I've put it on my own site for now.

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matrix inversion
by Umut Tabak 31 Jan '07

31 Jan '07

hi list, I have been experimenting to find the incerse aof a matrix with ublas but there is a problem: I have been looking at the code on http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?LU_Matrix_In… But there is sth wrong with that code because assign function template does not take a ublas::matrix<> as a direct parameter, it should ne converted to a matrix_expression but how may I do that. I did the inversion by using the assignment operator but wondered how it could be done thorough assign function template. The code on the viki works if you change the line with the assign to inverse=ublas::identity_matrix<T>(A.size1()); Maybe it can be of help. My best,

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Re: [Boost-users] problems with serialization library
by mauro gargano 31 Jan '07

31 Jan '07

thanks a lot Mark Wyszomierski!

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Question about using Boost::for_each function to set a local variable if a condition is met
by Meryl Silverburgh 31 Jan '07

31 Jan '07

Hi, I am trying to Boost::for_each function to set a local variable if all elements in this is DEFAULT type. Here is my code, but I don't know how to implement the last part of the if_then call. boolean rtnValue = false; for_each(mylist.begin(), mylist.end(), if_then( bind(&ListItem::getType, _1) == DEFAULT, set the local value to true if true if all of them are DEFAULT type )); if you can give me some pointers, I will be appreciated. Thank you.

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Open file name starting with "." in boost::filesystem
by Peng Yu 31 Jan '07

31 Jan '07

Hi, The following program gives some error. Can somebody let me know if it is possible to open filenames starting with "."? Thanks, Peng int main() { boost::filesystem::ofstream file(".abc"); } $ ./main-g.exe terminate called after throwing an instance of 'boost::filesystem::filesystem_error' what(): boost::filesystem::path: invalid name ".abc" in path: ".abc" Aborted

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[boost.threads] condition api question
by Frank Mori Hess 30 Jan '07

30 Jan '07

I'm curious why the boost::condition class requires a seperate mutex object to be created, and a corresponding scoped lock argument passed to the wait functions. Wouldn't it be easier to just keep a mutex inside the condition object and automatically lock it at the beginning of the wait functions? What am I missing here? -- Frank

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[lexical_cast] converting "true" to bool fails - why?
by Markus Werle 30 Jan '07

30 Jan '07

Hi! The following code snippet prints "failure!" during execution: #include <boost/lexical_cast.hpp> #include <iostream> int main() { try { bool test = boost::lexical_cast<bool>("true"); } catch (boost::bad_lexical_cast const &) { std::cerr << "failure!\n"; } } IIRC there was some way to achieve a conversion using the correct locale and stringstreams. Is there a way to obtain a successful conversion with lexical_cast, too? Markus

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[BGL] Problems with remove_vertex
by Adrian Boeing 30 Jan '07

30 Jan '07

Hi, I have a an adjacency_list graph, which I've been using fine. I would like to remove a vertex from the graph, and I do so by calling: clear_vertex then remove_vertex If I then try a call to: adjacent_vertices on a vertex that used to have the removed vertex as a parent, my program then crashes on the line 1481 "boost::tie(first, last) = out_edges(u, g);" of adjacency_list.hpp I'm using MSVC8.0 Any advice on what might be going wrong would be much appreciated. Thanks, -Adrian

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[BGL] vertices creates new objects
by George Sakkis 30 Jan '07

30 Jan '07

I've just started playing with the python bindings of BGL and I'm puzzled from the following: >>> from boost.graph import Graph >>> g = Graph() >>> v = g.add_vertex() >>> g.vertices.next() == v True >>> g.vertices.next() is v False It seems that the vertices iterator creates new vertex objects every time instead of iterating over the existing ones. This essentially prevents, among other things, storing vertices as keys in a dictionary since the hashes of the stored and the new vertex differ although they compare equal. Is this really what's happening, and if so, why ? Thanks, George

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what is the proper path setup?
by Ferng, Andrew D 30 Jan '07

30 Jan '07

I'm installing boost 1.33.1 on AIX 5.3 My home directory is /acct/a/adf After 'make install', it is in /DIR_Boost so I have the following: /acct/a/adf/DIR_Boost/include /acct/a/adf/DIR_Boost/lib All the hpp are in: /acct/a/adf/DIR_Boost/include/boost-1_33_1/boost Now I'm trying a sample program in /acct/a/adf/BOOST When I compile with 'g++ c.cpp' I get: > g++ c.cpp c.cpp:10:28: error: boost/config.hpp: No such file or directory c.cpp:15:42: error: boost/graph/adjacency_list.hpp: No such file or directory c.cpp:16:48: error: boost/graph/connected_components.hpp: No such file or directory c.cpp: In function 'int main(int, char**)': c.cpp:41: error: 'boost' is not a namespace-name c.cpp:41: error: expected namespace-name before ';' token c.cpp:43: error: expected initializer before '<' token c.cpp:45: error: 'Graph' was not declared in this scope c.cpp:45: error: expected `;' before 'G' c.cpp:46: error: 'G' was not declared in this scope c.cpp:46: error: 'add_edge' was not declared in this scope c.cpp:51: error: 'num_vertices' was not declared in this scope c.cpp:52: error: 'connected_components' was not declared in this scope The headers are: #include <boost/config.hpp> #include <iostream> #include <vector> #include <algorithm> #include <utility> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> In .cshrc, I've already got: set path=(~/DIR_Boost/include/boost-1_33_1 ~/gcc/usr/local/bin $path) Did I build boost incorrectly or am I just missing some path setup? Thanks!

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