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Bug in Ublas' Inner Product between Matrix and Vector?
by Gundala Viswanath 30 Jan '09

30 Jan '09

Hi all, I am trying to perform an inner product multiplication with ublas between this Matrix and Vector: ublas::matrix <double> inputMat (5,5,0); [5,5]((0.994704,0.000882587,0.000882587,0.000882587,0.00264776),(0.00527045,0.989459,0.00263523,0.00263523,0),(0,0,0.00528298,0,0),(0,0,0,1,0),(0,0,0,0,1)) ublas::vector <double> inputVec (5); [5](0.4,0.2,0.2,0.2,0.2) The result I get is this: [5](0.398941,0.201054,0.0010566*,0.2,0.2) Where as the correct one should be (using R): 0.3999707,0.1981258,0.2007013*,0.2007013,0.2005310 Note the significant discrepancy in the 3rd element (*). The product command I use is this: ublas::vector <double> Result (5); Result = ublas::prod(inputMat,inputVec); Is there anything wrong with my way of doing inner product or it is a bug? - Gundala Viswanath Jakarta - Indonesia

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linking boost in a shared library using -fPIC
by jono 30 Jan '09

30 Jan '09

hi. i'm building a shared library under gcc 4.1.1 which links some boost 1.33.1 libraries. a predecessor added the -fPIC switch to the Jamfiles of boost 'thread', 'date_time' and 'regex', and i have had no problems linking them. i've added the boost 'filesystem' library to the project and similarly patched the Jamfile... . . . lib boost_filesystem : ../src/$(SOURCES).cpp : # build requirements <define>BOOST_FILESYSTEM_STATIC_LINK <include>$(BOOST_ROOT) <sysinclude>$(BOOST_ROOT) <no-warn>exception.cpp <no-warn>operations_posix_windows.cpp #******************** <gcc><*><cxxflags>"-fPIC" #******************** # common-variant-tag ensures that the library will # be named according to the rules used by the install # and auto-link features: common-variant-tag : debug release # build variants ; . . . ... and recompiled boost. but i still get the following linker error. ------------------------------------------------------------- gcc-Link-action bin/blablabla/libinterpreter.so/gcc/debug/shared-linkable-true/threading-multi/libinterpreter.so /usr/bin/ld: /home/jono/lib/boost/bin_linux/debug/libboost_filesystem.a(operations_posix_windows.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC /home/jono/lib/boost/bin_linux/debug/libboost_filesystem.a: could not read symbols: Bad value ------------------------------------------------------------- can anyone spot my deliberate mistake? cheers Jono

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from range_iterator to range_value
by er 29 Jan '09

29 Jan '09

Hello, Is this, or a class that achieves the same goal, already defined somewhere in the boost? template<typename R> struct range_value{ typedef typename iterator_value<typename boost::range_iterator<R0>::type>::type type; }; Thanks.

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[serialization] Support for smart pointers?
by Robert Dailey 29 Jan '09

29 Jan '09

Hi, The documentation for Boost.Serialization states that support for loading/saving pointers is fully supported out of the box. However, what if I want to use smart pointers, such a boost::scoped_ptr? Right now I believe I would have to do this: Foo* foo1; archive & foo1; boost::scoped_ptr<Foo> foo2( foo1 ); I was thinking it would be convenient to avoid the extra variable (foo1) and do this: boost::scoped_ptr<Foo> foo2; archive & foo2; Is this possible?

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[lambda] lambda member access
by Michał Nowotka 29 Jan '09

29 Jan '09

In function: void clean_data (MyMap& map) { remove_if(map.begin(), map.end(), (&lambda::_1 )->*(&pair< X* const, double >::second) <= m_epsilon); } where: typedef std::map<const X*,double> MyMap; I get error: c:\program files\microsoft visual studio 9.0\vc\include\algorithm(1240) : error C2582: 'operator =' function is unavailable in 'std::pair<_Ty1,_Ty2>' with [ _Ty1=const hapl::Haplotype *const , _Ty2=double ] c:\program files\microsoft visual studio 9.0\vc\include\algorithm(4949) : see reference to function template instantiation '_OutIt std::_Remove_copy_if<std::_Tree<_Traits>::iterator,_OutIt,_Pr>(_InIt,_InIt,_OutIt,_Pr,std::_Range_checked_iterator_tag)' being compiled with [ _OutIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator, _Traits=std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>, _Pr=boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::lessorequal_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::other_action<boost::lambda::member_pointer_action>>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::addressof_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,double std::pair<hapl::Haplotype *const ,double>::* const ,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,const double,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>, _InIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator ] c:\program files\microsoft visual studio 9.0\vc\include\algorithm(1309) : see reference to function template instantiation '_OutIt stdext::unchecked_remove_copy_if<std::_Tree<_Traits>::iterator,_FwdIt,_Pr>(_InIt,_InIt,_OutIt,_Pr)' being compiled with [ _OutIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator, _Traits=std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>, _FwdIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator, _Pr=boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::lessorequal_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::other_action<boost::lambda::member_pointer_action>>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::addressof_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,double std::pair<hapl::Haplotype *const ,double>::* const ,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,const double,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>, _InIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator ] c:\users\kott\documents\visual studio 2008\projects\mbi\implementation\src\main.cpp(631) : see reference to function template instantiation '_FwdIt std::remove_if<std::_Tree<_Traits>::iterator,boost::lambda::lambda_functor<T>>(_FwdIt,_FwdIt,_Pr)' being compiled with [ _FwdIt=std::_Tree<std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>>::iterator, _Traits=std::_Tmap_traits<const hapl::Haplotype *,double,std::less<const hapl::Haplotype *>,std::allocator<std::pair<const hapl::Haplotype *const ,double>>,false>, T=boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::lessorequal_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::other_action<boost::lambda::member_pointer_action>>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::addressof_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,double std::pair<hapl::Haplotype *const ,double>::* const ,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,const double,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>, _Pr=boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::relational_action<boost::lambda::lessorequal_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::other_action<boost::lambda::member_pointer_action>>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::addressof_action>,boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>>,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,double std::pair<hapl::Haplotype *const ,double>::* const ,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>>,const double,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>>> ] I don't get it because i found somewhere (http://www.lukaszczerwinski.pl/boost_lambda_member_access.html) similar example that (should) work fine: std::map< std::string , int > someMap; using boost::lambda::_1; std::for_each( someMap.begin(), someMap.end(), std::cout << ( & _1 ) ->* ( & std::pair< std::string const, int >::first ) << std::endl ); -- Michał Nowotka

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[Thread] How to invoke a memory fence?
by Radosavljevic, Branko 29 Jan '09

29 Jan '09

I have a newbie question about using Boost.Thread to invoke a memory fence operation. What are the memory fence guarantees associated with the synchronization concepts in Boost.Thread? My specific use case involves one writer and several readers. For example, something like: bool available = false; int value; // Writer thread value = getValue(); available = true; // A reader thread while (!available) yield(); doSomething(value); In other words, the write to available should have release semantics, and the read from available should have acquire semantics. I realize I can use platform-specific commands, but I'd rather not. I assume that if I want to use Boost.Thread, I'll need to use a mutex, but I don't see any discussion of memory fence issues in the documentation. Thanks, Branko Any information contained in or attached to this e-mail is intended solely for the use of the intended recipient(s), is confidential and may contain information that is legally privileged. If you are not an intended recipient of this e-mail, please notify the sender of the delivery error and then please delete and destroy all copies and attachments, and be advised that any review or dissemination of, or the taking of any action in reliance on, the information contained in or attached to this e-mail is expressly prohibited. See http://www.bankofamerica.com/emaildisclaimer (if this link is not clickable, please copy and paste the link into your browser address bar) for further important information on confidentiality, the risks inherent in electronic communication (including the possibility that e-mail messages cannot be guaranteed to be secure or free of errors or viruses), some of our policies regarding transactions and pricing and certain other matters.

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BOOST_NO_EXCEPTIONS problem when C++ Exceptions are disabled
by rroc 29 Jan '09

29 Jan '09

Hi, I 'm trying to create a msvc project with C++ Exceptions disabled, as well as defined BOOST_NO_EXCEPTIONS and _HAS_EXCEPTIONS=0. This requires me to define a custom exception routine. All of this goes smoothly, but there is a problem with boost. Even when the BOOST_NO_EXCEPTIONS is set, the following boost files: exception\diagnostic_information.hpp exception_ptr.hpp ...are using try-catch blocks and because of this give a warning: warning C4530: C++ exception handler used, but unwind semantics are not enabled. Am I using this somewhat wrong or should I just modify the files to for example always ::boost::throw_exception()? Thanks, Johannes Rajala -- View this message in context: http://www.nabble.com/BOOST_NO_EXCEPTIONS-problem-when-C%2B%2B-Exceptions-a… Sent from the Boost - Users mailing list archive at Nabble.com.

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[partly: Boost.Function] typesafe (templated) wrapper around class with void* API
by Christoph Duelli 29 Jan '09

29 Jan '09

[This question has a Boost.Function relation later on. Sorry if too off topic.] I have a class that works on some data structures. This class' API uses void* to be general and avoid code duplication that using a template here would incur. Basically: class A // simplification { // Assume A to be a "fat" class there are more methods // working on void* // and lots of code put away into a .cpp file. We don't // want that duplicated by many template instantiations. public: // Most of the work is generic and independent from the // data types worked on. void do_something(void*); protected: // some work has to be done be the subclass virtual bool help_me(const void*) =0; }; I do not like using void* all that much. Thus I would like to create a type-safe (generic) thin wrapper class. Using inline functions,the idea is that the run time penalty (at least for do_something) is low and casts from/and to void are all 'hidden' here. template<typename T> class B : public A { public: void do_something(T* t) { A::do_something(t); } protected: // Force user to provide a correctly typed callback. virtual bool help_me(const T*) =0; private: // call the user's safe callback bool help_me(const void* t) { return help_me(static_cast<const T*>(t)); } }; and finally class C : public B<MyStruct> { bool help_me(const MyStruct* ms) { ... } }; Is this a good way to do that? More specific questions: i) I assume the penalty for my callback "help_me" is one more indirection. Can't see that optimized away. ii) Assuming A's interface gets passed a real callback function (a Boost.Function) instead: class A { public: typedef boost::function<bool(const void*)> helper_func; void do_something(void*, helper_func); }; is it somehow possible to get a typesafe templated B such that template<typename T> class B : public A { public: typedef boost::function<bool(const T*)> helper_func; void do_something(T* t, helper_func hf) { // this makes my compiler unhappy (when instanced). // I do understand that... can it be worked around somehow? A::do_something(t, hf); } }; I would like to be able to pass a function working on T* rather than void*. While writing this posting have found the following to compile: template<typename T> struct ToVoidWrapper { typedef boost::function<bool(const T*)> helper_func; helper_func hf_; ToVoidWrapper(const helper_func &hf) : hf_(hf) {} bool func(const void *t) const { return hf_(static_cast<const T*>(t)); } }; with do_something in B: void do_something(T* t, helper_func hf) { ToVoidWrapper<T> vw(hf); A2::do_something(t, boost::bind(&ToVoidWrapper<T>::func, &vw, _1)); } I am not really looking forward to writing such "forwarding to void*" functions. Are there alternatives? Maybe something in Boost that I have overlooked? Or a standard C++ idiom I am not aware of? I have attached compilable code that sums up the above code snippets so far. Thank you for looking into this and best regards Christoph

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Help with (possibly MPL) pattern for a viewer that may contain a copy of statically allocated data
by Jesse Perla 29 Jan '09

29 Jan '09

I am wondering what the best pattern/approach for a data structure that may contain either a reference or a copy of some data used in a constructor. I would love the opportunity to have the data structure capable of conditionally storing the data for the data copy on the stack. Are there any fancy generic tricks/patterns to do this using boost::mpl, etc.? So to put in some pseudocode notes for discussion to get the point across of what I think I want: boost::array< boost::array<double, M>, N> myaxis; //creates axis in a stack allocated data structure. regular_grid<M, N, COPYDATA> my_grid(axis_values); regular_grid<M, N, REFDATA> my_grid(axis_values); template<int M, int N, int ConstructionPolicy> class regular_grid { boost::array< boost::array<double, M>, N>& axis_ref_; //Reference to the axis, either static or actual reference. All code in the class would use this, not axis_ STATIC_IF(ConstructionPolicy == COPYDATA) { boost::array< boost::array<double, M>, N> axis_; regular_grid(const boost::array< boost::array<double, M>, N>& axis) : axis_(axis), axis_ref_(axis_) //constructor makes copy, sets ref to copy. { } } STATIC_ELSE(ConstructionPolicy == REFDATA) { regular_grid(const boost::array< boost::array<double, M>, N>& axis) : axis_ref_(axis) {} //constructor just uses the ref. } }; Is this possible? any ideas on code to look at to see how to do it?

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[lambda] newbie: lambda to help in std::accumulate
by Michał Nowotka 29 Jan '09

29 Jan '09

I want to compute sum of logarithms so i wrote: #include <cmath> double evaluate(const vector<double>& win_probabls) { return accumulate (win_probabls.begin(), win_probabls.end(), 0, lambda::_1 + log(lambda::_2) ); } but this code doesn't compile. Does anyone know why? -- Michał Nowotka

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