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Problem with user defined Boost Units system
by Stephen Torri 01 Dec '11

01 Dec '11

I am using Boost 1.45 and trying to use Boost Units to map the types of astrodynamic equation variables. I am getting an error with the following equation. The error is saying that the lvalue type for k2_divded_by_semi_major is wrong. The questions I have are: Q1: Did I defined my system correctly? (System file is attached - types.hpp) Q2: How do I define ratio in the system? For example I have some constants that define a conversion (1 earth radii = 6378 km). Q3: How do I define a variable type if its a fraction (e.g. radii / radian )? ---- EQUATION ---- sgp4::types::radii_t k2_divided_by_semi_major = m_k2 / pow<2> ( semi_major ); The types of variables are: m_k2 sgp4::types::radii_t semi_major sgp4::types::radian_t ---- ERROR ---- 1> [ 1> Unit=boost::units::unit<boost::units::list<boost::units::dim<boost::units::length_base_dimension,boost::units::static_rational<-1>>,boost::units::detail::merge_dimensions_impl<0,0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>,boost::units::homogeneous_system<boost::units::list<sgp4::types::radii_base_unit,boost::units::list<sgp4::types::radian_base_unit,boost::units::dimensionless_type>>>>, 1> Y=double 1> ] 1> and 1> [ 1> Unit=sgp4::types::sgp4_length_t, 1> Y=double 1> ] 1> Constructor for class 'boost::units::quantity<Unit,Y>' is declared 'explicit' 1> with 1> [ 1> Unit=sgp4::types::sgp4_length_t, 1> Y=double 1> ] Regards, Stephen

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Multicast using Asio
by Vince Deters 01 Dec '11

01 Dec '11

Hi, I'm working on a rudimentary pub/sub mechanism using Asio, with the requirement that the publisher be notified when a new subscriber appears. Using multicast, this would correspond to a subscriber joining the multicast group. But it appears there's no way for the publisher to know this, correct? If so, is the only alternative to dedicate a socket to each pub/sub pair? Thanks, Vince

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[Units] Temperature conversion problem
by Belcourt, Kenneth 01 Dec '11

01 Dec '11

Hi, There appears to be a temperature conversion problem between ºC and ºF. Here's a simple test that shows the error under both gcc and Intel on both Darwin and Linux (with Boost trunk). brisc:~ kbelco$ cat test3.cpp #include <iostream> #include <boost/units/io.hpp> #include <boost/units/quantity.hpp> #include <boost/units/systems/temperature/celsius.hpp> #include <boost/units/systems/temperature/fahrenheit.hpp> int main(int, char **) { using namespace boost::units; quantity<fahrenheit::temperature> t(100 * celsius::temperature()); // expect output of 212 F, produces 180 F // seems like not adding 32º offset when computing F = (C * 9/5 + 32) std::cout << t << std::endl; return 0; } brisc:~ kbelco$ icpc -g -Iboost test3.cpp brisc:~ kbelco$ ./a.out 180 F -- Noel

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Re: [Boost-users] [Units] Temperature conversion problem
by Alex Perry 01 Dec '11

01 Dec '11

On Wed, 30 Nov 2011 15:00:28 -0800 Matthias Schabel <boost(a)schabel-family.org> wrote: ...snip... > This will have the added benefit of allowing conversions but disallowing > operations that don't make sense... Some code: > > #include <iostream> > > #include <boost/units/absolute.hpp> > #include <boost/units/systems/temperature/celsius.hpp> > #include <boost/units/systems/temperature/fahrenheit.hpp> > #include <boost/units/systems/si/temperature.hpp> > > #include <boost/units/base_units/temperature/conversions.hpp> > > using namespace boost::units; > > int main() > { > quantity<celsius::temperature> > dTC(10.*celsius::temperature()); > quantity<fahrenheit::temperature> > dTF(10.*fahrenheit::temperature()); > quantity<si::temperature> dTK(10.*si::kelvin); > > std::cout << dTC << std::endl; > std::cout << dTF << std::endl; > std::cout << dTK << std::endl; > > quantity<absolute<celsius::temperature> > > TC(0*absolute<celsius::temperature>()); > quantity<absolute<fahrenheit::temperature> > > TF(32.*absolute<fahrenheit::temperature>()); > quantity<absolute<si::temperature> > > TK(0.*absolute<si::temperature>()); > > std::cout << TC << std::endl; > std::cout << TF << std::endl; > std::cout << TK << std::endl; > > std::cout << quantity<absolute<celsius::temperature> >(TF) << > std::endl; > std::cout << quantity<absolute<celsius::temperature> >(TK) << > std::endl; > > std::cout << quantity<absolute<fahrenheit::temperature> >(TC) << > std::endl; > std::cout << quantity<absolute<fahrenheit::temperature> >(TK) << > std::endl; > > // std::cout << TC+quantity<absolute<celsius::temperature> >(TF) << > std::endl; // fails because you cannot add two absolute temperatures > std::cout << TC+quantity<celsius::temperature>(dTF) << std::endl; > std::cout << TF+quantity<fahrenheit::temperature>(dTC) << > std::endl; > > return 0; > } Not being a current user of boost units I was curious about above code and just thought I'd try it (it looked totally straightforward and I was thinking hmm maybe I should be using boost units at times) - However it didn't compile (msvc 2010 and boost 1.48) - It wasn't exactly hard to change it so it would compile - just played around a little and ended up adding :- #include <boost/units/quantity.hpp> #include <boost/units/io.hpp> However given your email had outputs pasted in so obviously code was running at some point I wondered : Was this just a cut & paste typo? Or do you need to be careful with headers in code using boost unit to make sure that it compiles x-platform or some such? Alex

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[phoenix] problem when trying to access member via arg1
by Christian Hoffmann 01 Dec '11

01 Dec '11

Hi, I have below test program in which I try to call a function on each map object. It compiles and runs fine with gcc 4.5 but not on vc10. Is arg1 and ->* operator supposed to work when arg1 is an object and not pointer? Or is there another way of accessing members with arg1 (i.e. without phoenix::bind)? Regards, Chris ----------------------- #include <boost/phoenix/core.hpp> #include <boost/phoenix/operator.hpp> #include <iostream> #include <vector> #include <boost/range/algorithm.hpp> #include <boost/shared_ptr.hpp> #include <boost/shared_ptr.hpp> struct A { void f (int s) const { std::cout << "Calling f (" << s << ")...\n"; } }; int main (int argc, const char **argv) { typedef std::map<int, boost::shared_ptr<A> > map_type; typedef map_type::value_type value_type; map_type a_map; a_map[3] = boost::shared_ptr<A> (new A ()); namespace phoenix = boost::phoenix; using phoenix::arg_names::arg1; boost::for_each (a_map, ((arg1->*&value_type::second)->*&A::f) (10)); } ---------------------------

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Subversion repository not accessible as anonymous
by Marko Lindqvist 01 Dec '11

01 Dec '11

http://www.boost.org/users/download/#repository says that "Anonymous, read-only access to the Boost Subversion repository is available at http://svn.boost.org/svn/boost." My attempts to make checkout results in svn prompting for credentials. Seems like misconfiguration to me. - ML

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Using hash_range with polymorphism
by Kelvin Chung 01 Dec '11

01 Dec '11

I'm having a hard time reconciling two distinct notions. Suppose I have a class hierarchy with root class Foo, and subclasses Foo1, Foo2, etc. (all of which are leaf classes) Now, suppose that hash_value() is defined for all the subclasses but not Foo itself (say, if Foo was abstract). Now suppose I have this: struct FooList { std::vector<boost::shared_ptr<Foo>> foos; } std::size_t hash_value(const FooList& list) { std::size_t seed = 0; typedef boost::indirect_iterator<std::vector<boost::shared_ptr<Foo>>::const_iterator> Iterator; boost::hash_range(seed, Iterator(list.foos.begin()), Iterator(list.foos.end()); return seed; } This seems a bit incorrect (and it would fail to compile due to "ambiguous overload" of hash_combine or something). What I want to do is something along the lines of std::size_t hash_value(const FooList& list) { std::size_t seed = 0; for (std::vector<boost::shared_ptr<Foo>>::const_iterator it = list.foos.begin(); it != list.foos.end(); ++it) { boost::hash_combine(seed, **it); } return seed; } That is, hash the Foos pointed to by the foos (using the correct derived class hash_value() functions) and not the shared_ptrs themselves. Is there a "shorter" version of the latter (which I presume is correct), or will the latter have to do?

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fusion newby question - boost stew
by Robert Ramey 01 Dec '11

01 Dec '11

I'm experimenting with fusion and I have a question regarding the compatibiliy/interaction with MPL. in .. /libs/fusion/doc/html/fusion/introduction.html it states: "Fusion provides full round compatibility with MPL. Fusion sequences are fully conforming MPL sequences and MPL sequences are fully compatible with Fusion. You can work with Fusion sequences on MPL if you wish to work solely on types [1]. In MPL, Fusion sequences follow MPL's sequence-type preserving semantics" So when I compare the pages for the concept of AssociativeSequence for fusion: libs/fusion/doc/html/fusion/sequence/concepts/associative_sequence.html and that for MPL libs/mpl/doc/refmanual/associative-sequence.html the expression requirements are not the same. The metafunctions for fusion are: result_of::has_key<S, K>::type result_of::at_key<S, K>::type result_of::value_at_key<S, K>::type while for MPL they are has_key<s,k>::type count<s,k>::type order<s,k>::type at<s,k>::type at<s,k,def>::type key_type<s,x>::type value_type<s,x>::type So how can the statement in the fusion introduction be true? This question comes about as I'm making a new "thing" of my own invention where I want to inter-operate with purely type sequences created with MPL - just likt it says you can do in the documentation. Turns out at significant part of this "boost stew" depends on better compile time checking of the users's metafunction invocation. This ends up creating the need for concepts in both MPL which as far as I know haven't yet been coded. So when I do this, I run accross this question. I realize I can build a fusion sequence from an MPL one, but given the language in the introduction, I would have expected to be able to go both ways and this wouldn't seem to be true. Note that it's quite possible that I'm missing something here as I feel that I'm really starting to get this stuff only for the first time. Robert Ramey

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FW: BGL, MPI
by Neiderer, Andrew M USA CIV (US) 01 Dec '11

01 Dec '11

With lots of help I think I am getting close to a "hello, world" BGL, MPI example to execute. Not sure about the error I am getting from execution from libs/mpi/example on symmetric multiprocessing (SMP) cluster of compute nodes, 1. compilation/translation of hello_world.cpp, works :-) $ mpiCC -I ../boost_1_48_0 \ -I ../boost_1_48_0/boost/mpi \ -I ../boost_1_48_0/stage/lib \ -lboost_mpi \ -lboost_thread \ -lboost_regex \ -lboost_graph -lboost_graph_parallel \ -lboost_serialization \ -lpthread \ hello_world.cpp -o hello_world 2. execution, error :-( $ mpirun -np 2 ./hello_word *** Process received signal *** Signal: Segmentation fault (11) *** Signal code: Address not mapped (1) *** Failing at address (nil) *** /lib64/libpthread.so.0 *** mpirun noticed process rank 0 with PID 16684 Maybe someone has seen this before and knows of a fix. Thank you. Andrew M. Neiderer US Army Research Lab

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Multi_array still incompatible with VS2010 Debug
by Michael Jackson 30 Nov '11

30 Nov '11

Are there any plans to update multi_array to be compatible with VS2010? Kind of an issue when I try to compile my code using VS2010? Searching around it seems that this bug has been around for a while now. There is even a suggested fix in one of the bugs. Thanks Mike Jackson

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