- Boost-users - lists.boost.org

RE: [Boost-Users] Possible boost addition: sub string and const s tring.
by Jim.Hyslop 19 Nov '02

19 Nov '02

Forwarded to main Boost list - that's the more appropriate venue for discussions of possible additions. -- Jim Hyslop boost-users moderator. > -----Original Message----- > From: alexei_novakov [mailto:alexei_novakov@yahoo.com] > Sent: Monday, November 18, 2002 7:05 PM > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Possible boost addition: sub string and const > string. > > > Hello everyone. > > I have two classes which I found pretty handy: sub_string (behaves as > a mirror of the portion of master basic_string) and const_string (C- > string wrapper). Nice thing about these two is they implemented as > template specialization of basic_string which has advantages: > a) familiar interface; > b) possibility to reuse the code written for basic_string (like > string streams, lexical casts, etc). > > Any interest? > > Regards. > > Alexei Novakov > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > >

1 0

which compiler are you using while using bgl?
by Jun Zhang 19 Nov '02

19 Nov '02

I am a newbie from China, I am sorry about my poor English. I encountered a problem while using bgl. I need your help. and I'd like to know what compiler you are using while using bgl. My Environment: Windows2000 + devc++4.9.6.0(it uses g++ as it's compiler) But it can't compile and run the following example: _________Example start____________ #include <deque> // to store the vertex ordering #include <vector> #include <list> #include <iostream> #include <boost/graph/vector_as_graph.hpp> #include <boost/graph/topological_sort.hpp> int main() { using namespace boost; //create each labels of the tasks const char* tasks[] = { "pick up kids from school", "buy groceries (and snacks)", "get cash at ATM", "drop off kids at soccer practice", "cook dinner", "pick up kids from soccer", "eat dinner"}; const int n_tasks = sizeof(tasks)/sizeof(char*); //create the graph std::vector<std::list<int> >g(n_tasks); g[0].push_back(3); g[1].push_back(3); g[1].push_back(4); g[2].push_back(1); g[3].push_back(5); g[4].push_back(6); g[5].push_back(6); // perform the toplogical sort and output the result std::deque<int> topo_order; topological_sort(g, std::front_inserter(topo_order),vertex_index_map(identity_property_map())); int n = 1; for (std::deque<int>::iterator i = topo_order.begin();i != topo_order.end(); ++i, ++n) std::cout << tasks[*i] << std::endl; system("PAUSE"); } _________Example End_____________ it says: 36 ...\main.cpp instantiated from here I wondered it can compile another example:file_dependencies.cpp, which has also used topological_sort.

4 5

Boost::Threads building ".a" file for MinGW
by ian_ganigan 19 Nov '02

19 Nov '02

Need help ASAP.. I'm new at this. Anyone?

1 0

Possible boost addition: sub string and const string.
by alexei_novakov 19 Nov '02

19 Nov '02

Hello everyone. I have two classes which I found pretty handy: sub_string (behaves as a mirror of the portion of master basic_string) and const_string (C- string wrapper). Nice thing about these two is they implemented as template specialization of basic_string which has advantages: a) familiar interface; b) possibility to reuse the code written for basic_string (like string streams, lexical casts, etc). Any interest? Regards. Alexei Novakov

1 0

Forte 7 Compiler
by ewanbrock 18 Nov '02

18 Nov '02

Hi, I'm trying to compile Boost using the Solaris Forte 7 Compiler. Initial attempts are leading to all sorts of assertion errors. Has anyone had success using boost with this compiler? Does anyone know what the Config options should be ? Many thanks, Ewan

1 0

[BGL] vc6&7 doesn't support partial specialization,can I still use BGL in vc?
by Jun Zhang 18 Nov '02

18 Nov '02

I can't believe it is vc7!! still missing support for partial specialization. Do you know other method to let vc compile BGL codes used partial specialization? Need your help. Jun Zhang

1 0

adjacency_list going out of memory range?
by Ramón Casero Cañas 18 Nov '02

18 Nov '02

Hi, I'm working with GNU/Linux, Debian Sarge, libboost-graph1.28.0, gcc version 2.95.4 20011002 (Debian prerelease). I'm quite new to this, so I don't know if I'll be able to explain my problem correctly. It seems to me as if when I declare a graph, it writes on memory already used by another data structure. The parts of the code that I consider relevant are (.hpp and .cpp merged) ------------------- | | \|/ ------------------- #include <utility> // for std::pair #include <boost/graph/adjacency_list.hpp>/* for namespace boost * vertex_index_t * edge_weight_t * listS * undirectedS */ using namespace boost; namespace boost { enum vertex_to_be_spanned_t { // used to mark vertices of W vertex_to_be_spanned }; BOOST_INSTALL_PROPERTY(vertex, to_be_spanned); } namespace steiner { typedef std::pair<int,int> Edge; // type of edges /* Steiner Problem Graph: * - multigraph * - add_edge(), ... stability and speed, bad space overhead * - vertex indices, edge weights */ typedef property <vertex_index_t, int, property <vertex_to_be_spanned_t, bool> > VertexProperty; typedef property <edge_weight_t, int> EdgeProperty; typedef adjacency_list <listS, listS, undirectedS, VertexProperty, EdgeProperty > SteinerGraph; } namespace steiner { #define EX_FORMAT "not a valid steiner problem file"; } #include <iostream> // for std::cout #include <fstream> // for std::ifstream using namespace steiner; namespace steiner { int readsteinerORfile(steiner::SteinerGraph& g, char *s); } namespace steiner { inline void skipspaces(std::ifstream& fp, char& c); } namespace steiner { inline int readchar2int(std::ifstream& fp, char& c); } /* int main(int argc, char *argv[]) * -------------------------------- * *argv[] (IN): file names array * -------------------------------- * return n: n files were succesfully read, n > 0 * return 0: no files could be read * return -1: unexpected error * -------------------------------- * read steiner problem from files */ int main(int argc, char *argv[]) { ... SteinerGraph g; nf = steiner::readsteinerORfile(g, argv[i]); ... } /* int readsteinerORfile(VertexListGraph& g, char *s) * -------------------------------- * g (OUT): graph read from file * *s (IN): file name * -------------------------------- * return 1: file successfully read * return 0: file could not be read * return -1: unexpected error * -------------------------------- * read steiner problem from one file */ namespace steiner { int readsteinerORfile(steiner::SteinerGraph& g, char *s) { ... int num_edg=0, num_ver=0, // number of edges, vertices num_verw=0; // number of non-steiner vertices char c; // file reader int i; // counter int x; // temp value int *weight_array=NULL; // edge weights read from file Edge *edge_array=NULL; // array of edges read from file int *w_array=NULL; // vertices of W ... weight_array = new int[num_edg]; if (weight_array == NULL) throw (char *)EX_MEM; edge_array = new Edge[num_edg]; if (edge_array == NULL) throw (char *)EX_MEM; w_array = new int[num_verw]; if (w_array == NULL) throw (char *)EX_MEM; ... *************** HERE ******************* /* creation of graph object */ g.clear(); g = SteinerGraph(num_ver); *************** HERE ******************* ... } } ------------------- | | \|/ ------------------- And what happens? If I print the contents of w_array[] at the first "HERE", I get Puf(W(0)=0 )! Puf(W(1)=1 )! Puf(W(2)=2 )! Puf(W(3)=3 )! but if I print them again at the second "HERE", I get Puf(W(0)=8 )! Puf(W(1)=1 )! Puf(W(2)=2 )! Puf(W(3)=-15 )! Does anybody knows what could be happening? Thank you. Regards, Ramón Casero.

2 2

RE: [Boost-Users] Getting a matrix to the power of n
by Scott Sinclair 17 Nov '02

17 Nov '02

Hi Unless I've missed something, I don't think uBlas provides a way to do this (other than the _very_ inefficient prod(A, A) in a loop). If you need to do this frequently with large matrices and/or large powers (n) then you'll need to look at diagonalizing your matrix using eigenvalue/vector decomposition. This reduces your task to raising the values on the diagonal of a diagonal matrix to the power of n and doing two matrix multiplies and an inverse. Finding the eigenvalues and corresponding eigenvectors of your matrix is a non-trivial task which imposes some restrictions on your matrix. Refer to "Numerical recipes in C" by Press et al. for some guidance as well as any good textbook on linear algebra. Hope this helps, Scott > -----Original Message----- > From: agiatojon [mailto:JonAgiato@nyc.rr.com] > Sent: 14/11/2002 14:17 > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Getting a matrix to the power of n > > > Hello all, > I am working with a formula which requires me to get the result of a > matrix to the power of n (i.e. pow(matrix, n)) but as expected, the > <cmath> function pow() is unable to convert from type double to > matrix. Does the matrix library have this sort of functionality > built in, or maybe some other part of boost? Thanks! > > Jon Agiato > JonAgiato(a)nyc.rr.com The contents of this email may be confidential. Unauthorised use is prohibited. Umgeni Water does not accept liability for any statements and opinions which are the sender's own view and not expressly made on its behalf.

3 2

Using multi_array/matrix to wrap a SAFEARRAY
by Nick Toze 17 Nov '02

17 Nov '02

Hello, I haven't really used C++ much (more Java and Eiffel), but now I am helping develop a C++ dll that will use matrices alot and will probably need to use SAFEARRAY to interface with Visual Basic (either directly or via COM). Also the group I'm in need to standardize on a matrix representation and it needs to be compatible with NAG. I've been trying to wrap a SAFEARRAY using a multi_array and I've got something that seems to work (see attached), but :-) I'm not sure how to go about passing these (i.e. multi_array, multi_array_ref, const_multi_array_ref) around as function arguments since they don't have any inheritance relationship. Do you have any suggestions on that? Maybe template functions could be used, but I'd like to keep my code fairly simple since I'm no expert. As an alternative the uBLAS container classes look very appropriate since I'll only be passing numbers and some of the algorithms could be useful (although I'll mostly be using NAG), but I couldn't quite see whether it is possible to use a uBLAS matrix as a view onto the data in a SAFEARRAY. Is it possible to attach a pointer to an array to a uBLAS matrix? This is the code I've got as an example for wrapping a SAFEARRAY: typedef boost::multi_array_ref<double, 2> dbl_matrix_ref; typedef boost::multi_array<double, 2> dbl_matrix; __declspec(dllexport) HRESULT __stdcall mmultiply(SAFEARRAY** sa1, SAFEARRAY** sa2, SAFEARRAY** result) { HRESULT hr; if ( result == NULL ) return E_INVALIDARG; if ( (*sa1)->cDims != 2 ) return E_INVALIDARG; if ( (*sa1)->cbElements != 8 ) return E_INVALIDARG; if ( (*sa2)->cDims != 2 ) return E_INVALIDARG; if ( (*sa2)->cbElements != 8 ) return E_INVALIDARG; long m1_dim0_sz, m1_dim1_sz, m2_dim0_sz, m2_dim1_sz; m1_dim0_sz = (*sa1)->rgsabound[0].cElements; m1_dim1_sz = (*sa1)->rgsabound[1].cElements; m2_dim0_sz = (*sa2)->rgsabound[0].cElements; m2_dim1_sz = (*sa2)->rgsabound[1].cElements; hr = SafeArrayLock( *sa1 ); if ( FAILED(hr) ) return hr; hr = SafeArrayLock( *sa2 ); if ( FAILED(hr) ) return hr; dbl_matrix_ref matrix1( (double*)(*sa1)->pvData, boost::extents[m1_dim1_sz][m1_dim0_sz], boost::fortran_storage_order() ); dbl_matrix_ref matrix2( (double*)(*sa2)->pvData, boost::extents[m2_dim1_sz][m2_dim0_sz], boost::fortran_storage_order() ); dbl_matrix matrix_result( boost::extents[matrix1.shape()[0]][matrix2.shape()[1]], boost::fortran_storage_order() ); for (dbl_matrix_ref::index i = 0; i != matrix1.shape()[0]; ++i) { for (dbl_matrix_ref::index j = 0; j != matrix2.shape()[1]; ++j) { double s = 0; for (dbl_matrix_ref::index k = 0; k != matrix1.shape()[1]; ++k) { s = s + matrix1[i][k] * matrix2[k][j]; } matrix_result[i][j] = s; } } SAFEARRAYBOUND rgsabound[2]; rgsabound[0].lLbound = 0; rgsabound[0].cElements = matrix_result.shape()[0]; rgsabound[1].lLbound = 0; rgsabound[1].cElements = matrix_result.shape()[1]; SAFEARRAY* lresult = SafeArrayCreate(VT_R8, 2, rgsabound); lresult->pvData = matrix_result.data(); hr = SafeArrayCopy( lresult, result ); if ( FAILED(hr) ) return hr; hr = SafeArrayDestroy( lresult ); if ( FAILED(hr) ) return hr; hr = SafeArrayUnlock( *sa1 ); if ( FAILED(hr) ) return hr; hr = SafeArrayUnlock( *sa2 ); if ( FAILED(hr) ) return hr; return S_OK; } Then I declare this in VBA with: Declare Function mmultiply Lib _ "D:\multiarray_test\Debug\multiarray_test" _ (a() As Double, b() As Double, c() As Double) As Long

2 1

using 'this' with shared_ptrs
by Stephen Crowley 17 Nov '02

17 Nov '02

How is someone supposed to use 'this' when setting a member of another class to point back to it? Here is an example.. when you run it, this will happen. constructor called 0x804af10 constructor called 0x804af48 destructor called 0x804af48 destructor called 0x804af10 destructor called 0x804af10 The last destructor is called twice! The only way I can think to get around this add a member to the class called "shared_ptr<MyClass> thisptr" which is initialized to "this" in the constructor and over-ride the assignment operator or something.. will that work? ------------------------ #include <boost/shared_ptr.hpp> #include <boost/weak_ptr.hpp> #include <iostream> using namespace std; using namespace boost; class MyClass; typedef shared_ptr<MyClass> MyClassPtr; class MyClass { public: MyClass(); ~MyClass(); MyClassPtr makeCopy(); MyClassPtr original; }; MyClass::MyClass() { cout << "constructor called " << this << endl; } MyClass::~MyClass() { cout << "destructor called " << this << endl; } MyClassPtr MyClass::makeCopy() { MyClassPtr mc(new MyClass); mc->original = MyClassPtr(this); return mc; } main() { MyClassPtr oc(new MyClass); MyClassPtr cc = oc->makeCopy(); // the problem lies here // when cc's reference count is 0 it will be deleted, which will // in turn decrease its 'original' reference count which will be 0, thus // causing it to be deleted as well even though it is still being used by oc! cc.reset(); } ----------------------------------- -- Stephen

2 2