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[units] implicit type conversions to specific unit quantity
by Michael Powell 17 Aug '15

17 Aug '15

Hello, I'd like to convert from an SI length quantity to a US inches quantity. I believe the following snippet will do what I want it to, but wanted to clarify if that was the case: http://www.boost.org/doc/libs/1_59_0/doc/html/boost_units/Quantities.html I am referencing the online docs, but needed some clarity in actually how to go about using it in practice: <code> using boost::units::si::meter_base_unit; using boost::units::us::inch_base_unit; // i.e. 0.3048 * 12 (inches/feet, feet/meter) BOOST_UNITS_DEFINE_CONVERSION_FACTOR(inch_base_unit, meter_base_unit, double, 3.6576); //... quantity<inch_unit> to_inches_length_quantity(quantity<length> const & L) { const quantity<inch_unit::unit_type> result_(L); return result_; } </code> Just besides that, there isn't a cleaner way of doing it? Some have mentioned going as far as creating a whole other system for my calculator's purposes, for example. Thank you... Best regards, Michael Powell

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Re: [Boost-users] Building Boost 1.59.0 on Solaris 11 with Solaris Studio 12.4
by Leo Carreon 17 Aug '15

17 Aug '15

From: Leo Carreon Sent: Sunday, August 16, 2015 8:39 PM To: Boost Users Mailing List Subject: Building Boost 1.59.0 on Solaris 11 with Solaris Studio 12.4 >>Hi Boosters, >>I have been attempting to build Boost 1.59.0 on Solaris 11 using Solaris Studio 12.4 in C++11 mode. >>So far, I have managed to locate on the web solutions to 3 issues. >>Now I’m down to 22 targets failing to build. >>Has anyone else attempted to do the same? I would appreciate it if you could share some of your fixes if you have any. >>Has anyone reported that they have been able to cleanly build in this environment? >>Kind regards, >>Leo This is an update of my previous mail. I now have fixed 4 issues instead of 3. I also had a look at the build log generated from the above. It appears that the following issues are the cause of the remaining build problems which I haven’t figured out how to resolve yet: 1. ) "libs/thread/src/pthread/thread.cpp", line 103: Error: The operation "boost::shared_ptr<boost::detail::tss_cleanup_function> && bool" is illegal. "libs/thread/src/pthread/thread.cpp", line 144: Error: Overloading ambiguity between "boost::call_once<void(*)()>(boost::once_flag&, void(*)())" and "boost::call_once<void(&)()>(boost::once_flag&, void(&)())". "libs/thread/src/pthread/thread.cpp", line 150: Error: Overloading ambiguity between "boost::call_once<void(*)()>(boost::once_flag&, void(*)())" and "boost::call_once<void(&)()>(boost::once_flag&, void(&)())". "libs/thread/src/pthread/thread.cpp", line 803: Error: The operation "bool && boost::shared_ptr<boost::detail::tss_cleanup_function>" is illegal. "libs/thread/src/pthread/thread.cpp", line 807: Error: The operation "boost::shared_ptr<boost::detail::tss_cleanup_function> || bool" is illegal. "libs/thread/src/pthread/thread.cpp", line 817: Error: The operation "boost::shared_ptr<boost::detail::tss_cleanup_function> || bool" is illegal. 2.) "./boost/thread/detail/nullary_function.hpp", line 125: Error: Cannot use std::shared_ptr<boost::detail::nullary_function<void()>::impl_base> to initialize bool. "./boost/thread/detail/nullary_function.hpp", line 125: Error: An expression of scalar type was expected. 3.) "libs/coroutine/src/posix/stack_traits.cpp", line 56: Error: Overloading ambiguity between "boost::call_once<void(&)(unsigned long*), unsigned long*>(boost::once_flag&, void(&)(unsigned long*), unsigned long*&&)" and "boost::call_once<void(*)(unsigned long*), unsigned long*>(boost::once_flag&, void(*)(unsigned long*), unsigned long*)". "libs/coroutine/src/posix/stack_traits.cpp", line 64: Error: Overloading ambiguity between "boost::call_once<void(&)(rlimit*), rlimit*>(boost::once_flag&, void(&)(rlimit*), rlimit*&&)" and "boost::call_once<void(*)(rlimit*), rlimit*>(boost::once_flag&, void(*)(rlimit*), rlimit*)". 4.) "./boost/proto/detail/preprocessed/make_expr_.hpp", line 73: Error: type is not a member of boost::proto::transform<boost::proto::switch_<boost::phoenix::phoenix_generator, boost::proto::tag_of<boost::proto::_>()>, void>::result<boost::phoenix::phoenix_generator(boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::assign, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::argument<1>>, 0>, boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::argument<1>>, 0>>>, 2>)>. 5.) "libs/python/src/converter/builtin_converters.cpp", line 474: Error: Overloading ambiguity between "std::complex<double>::complex(double, double)" and "std::complex<double>::complex(complex double[2])". "libs/python/src/converter/builtin_converters.cpp", line 474: Error: Cannot return long from a function that should return std::complex<double>. 2 Error(s) detected. 6.) "./boost/thread/once.hpp", line 38: Error: Overloading ambiguity between "boost::call_once<void(*)()>(boost::once_flag&, void(*)())" and "boost::call_once<void(*)()&>(boost::once_flag&, void(*)()&)". 7.) "./boost/spirit/home/classic/core/non_terminal/impl/object_with_id.ipp", line 145: Error: Overloading ambiguity between "boost::call_once<void(*)()>(boost::once_flag&, void(*)())" and "boost::call_once<void(&)()>(boost::once_flag&, void(&)())". 8.) "./boost/spirit/home/classic/phoenix/closures.hpp", line 427: Error: Overloading ambiguity between "boost::call_once<void(*)()>(boost::once_flag&, void(*)())" and "boost::call_once<void(&)()>(boost::once_flag&, void(&)())". These remaining issues are preventing me from building my own library because it depends on some of the Boost libraries that are still failing to build.

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Re: [Boost-users] [boost] Making the Windows binaries 'official'
by Tom Kent 15 Aug '15

15 Aug '15

On Fri, Aug 14, 2015 at 8:34 PM, Glen Fernandes <glen.fernandes(a)gmail.com> wrote: > On Fri, Aug 14, 2015 at 9:03 PM, Tom Kent wrote: > > Is this something the community would be in favor of? I know that many of > > the people on these lists don't use windows and if they do are generally > > capable of building the windows binaries themselves, however there is a > > large group out there that prefers to just get the installer for them > (like > > they do for other projects like Qt, wxWidgets, etc). > > > > Thoughts? > > While I have not been a MSVC user for a while now: I think it's a good > thing for our VC users that binaries are available to them. > > Is (1) necessary? I was under the impression binaries becoming > available a few days after a source release is not uncommon. > This is basically how it is now....if people don't think it is necessary we can stick with this. However, I think it would be more professional if we change, hence my e-mail to the list. > SourceForge raises the usual concern: Can you trust a Windows > executable or DLL that you get from sourceforge.net anymore? > The .7z file and installers are SHA-256 hashed, and the list of hashes is signed with my GPG key. That said, I think we need to start planning an alternative to sourceforge for releases. It is not clear to me that it will still be around in a few years. That's a whole different thread though. > > Also, how do you cater to users who want variants that you're not > providing? i.e. Already you probably have Debug/Release * > 32-bit/64-bit * MT/MD/MTd/MDd * LIB/DLL (per 6 compiler versions). > What happens if someone wants /Gz or /Gv instead of /Gd etc. > I provide whatever bjam specifies with --build-type=complete. The bigger question is external libraries. I link with zlib, and bzip2 but not MPI for instance. I have had users ask for different version numbers of those libraries, but my answer is then that you're on your own for building anything else. These kind of questions are only relevant to far less than 1% of the people who download the binaries. Tom

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[type_erasure] BOOST_TYPE_ERASURE_MEMBER with template?
by Nat Goodspeed 15 Aug '15

15 Aug '15

The code with which I'm working has two similar template classes: they have a common subset of 8 methods that could be used on an instance of either. For performance reasons, these methods are not virtual. As far as the compiler knows, the two template classes are unrelated. Naturally we can write a template function to accept an instance of either template class, as long as it uses only methods from the common subset. I also want to support runtime polymorphism, permitting a non-template function to accept an instance of either template class. Obviously that will incur some performance hit, but the coder can decide whether or not his/her function is performance-critical. If so, s/he can write that function to accept one or the other specific template class -- or write a template function. We want to incur the performance hit only when the coder deems that an acceptable tradeoff. The classic solution would be to derive both template classes from a common base class and make the common methods virtual -- but then that penalizes every consumer. I haven't yet used Boost.TypeErasure, but it seems to me potentially applicable to this problem. I see the example[0] illustrating use of BOOST_TYPE_ERASURE_MEMBER(). I was going to define requirements for each of the 8 common methods ... but then I became confused. Our common methods use a template parameter from the parent template class as a method parameter type. Can I invoke BOOST_TYPE_ERASURE_MEMBER in a generic way that would support all valid template parameters? Two of the 8 common methods are template methods, accepting a parameter whose type is a template parameter for the method rather than the containing class. I don't know whether that introduces further complexity. Thank you for any help you can provide! [0] http://www.boost.org/doc/libs/1_59_0/doc/html/boost_typeerasure/basic.html

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Making the Windows binaries 'official'
by Tom Kent 15 Aug '15

15 Aug '15

<history> After the boostpro.com organization dissolved, there was never an official place to go to get pre-built binaries for the releases. Some random components were made available on the sourceforge download page and I had been hosting them on my own website (http://boost.teeks99.com) since I started building them around the release of 1.37. A couple years ago, before the release of 1.54, I asked the community if they would like my builds to be hosted on the sourceforge site, and the answer was positive: http://lists.boost.org/Archives/boost/2013/04/202460.php Since the 1.54 release, I've generally been uploading the windows binaries based on the RCs and enabling the downloads just a few minutes after the release notice goes out. </history> I would now like to propose that we make these libraries an official part of each Boost release. I don't think this entails much, just the following: 1) Have the release team coordinate with me to ensure that the binaries are ready before announcing the release. 2) Include a link to them in the release announcement. 3) Link to them from the website. It would also be good to get others who can run the scripts to perform the build, if I am someday unable to do this. The biggest hurdle here is having a (virtual) machine with all six versions of visual studio on it. Is this something the community would be in favor of? I know that many of the people on these lists don't use windows and if they do are generally capable of building the windows binaries themselves, however there is a large group out there that prefers to just get the installer for them (like they do for other projects like Qt, wxWidgets, etc). Thoughts? Tom Kent

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[Graph] Descriptor invalidation on remove_vertex() with adjacency_list VL=vecS
by Chris Dellin 14 Aug '15

14 Aug '15

Hello, The documentation for the adjacency_list [0] is clear that if the vertex list container is vecS, then calling remove_vertex() will invalidate any vertex/edge descriptors into the graph. However, I was wondering if this is actually the case if the removed vertex was the one most recently added, that is, remove_vertex(vertex(num_vertices(g)-1)). In this case, I would think that no shifting of vertex data or adjustment of edge source/target indices would be necessary, and existing descriptors are guaranteed to be still valid. Is this safe to do with the current implementation? If not, why not? Thanks, - Chris Dellin [0] http://www.boost.org/doc/libs/1_59_0/libs/graph/doc/adjacency_list.html

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[shared_ptr] boost::shared_ptr deleter question
by Tamas.Ruszkai＠leica-geosystems.com 14 Aug '15

14 Aug '15

Hi All, I wonder when the shared_ptr deleter is destroyed. I have a shared_ptr with a custom deleter. I would expect when the last shared pointer to the object is gone then not only the deleter method will be called, but the deleter function object is also released. As I see the deleter is taken by value and stored by value in the reference counter, so I do not understand what is going on. How is the deleter mean to be freed? Thanks, Tamas struct MyClassDeleter { ~MyClassDeleter() { // Break point is set here } void operator()(MyClass* item) { // Break point is set here } } { auto sharedPtr = boost::shared_ptr<MyClass>(new MyClass, MyClassDeleter) } // shared_ptr leaves the scope here, the custom deleter is called (parenthesis operator) // the deleter instance is however not destroyed, the breakpoint in the destructor does not hit

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Log: Overwrite format of sink
by Florian Lindner 14 Aug '15

14 Aug '15

Hello, I have a console sink: boost::log::add_console_log(std::cout, keywords::format = fmtStream); with fmtStream being an expressions stream. After setting up the sinks I load a configuration file: std::ifstream file("log.settings"); init_from_stream(file); Is there a way to overwrite the format of this sink from within in the configuration file. Or, alternatively disable this sink. What I want to achieve is that a user have the option to modify the format without having two console outputs... Thanks, Florian

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Query regarding interest in my submitting plf::colony to Boost
by Soul Studios 14 Aug '15

14 Aug '15

Hi all, I've had some expressions of support outside of the Boost community for submission of the plf::colony container and it's associated container plf::stack, mainly from the review judges for my cppcon submission on the same topic (topic didn't make it through to the finals but got a positive response). I'd like to guage reactions here to see whether it is worth spending the time necessary to port it to Boost, with all the associated reviews etc. plf::colony is a container for unordered data, where erasure and addition do not cause iterator/pointer invalidation, with superior performance characteristics to all std:: containers when either (a) Pointers and iterators which point to container elements must stay valid regardless of container additions and deletions and/or (b) Additions to or deletions from the container will be occurring in performance-critical code. Erasure performance in particular can be in advance of 6000x of vectors, while still being faster than lists, maps, deques etc for add and iteration. Full details and benchmarks across four compilers are here: http://www.plflib.org/colony.htm#benchmarks It has been thoroughly tested, including integrating it into the game engine I constructed last year as well as the usual unit tests. It supports both C++0x and C++11, and has been tested on the following compilers so far: Clang 3.4, GCC 4.6, 4.7, 4.8, 4.9 and 5.1 (both 32-bit and 64-bit), MS Visual C++ 2010 & 2013 (2015 supported but untested as yet). Internally a colony is a combination of a linked-list of increasingly-larger memory blocks combined with boolean erasure fields, combined with a custom memory location recycle stack. The most common comment I get is "that sounds kinda like a deque", so to save some time here are the differences (from the FAQ): "A double-ended queue requires a very different internal framework. It may or may not use a linked-list of memory blocks, dependent on the compiler, and has no comparable performance characteristics. Deque element erasure is very slow, similar to a vector, and it does not free unused memory blocks to the OS once they are empty, unlike a colony. In addition a deque invalidates references to subsequent container elements when erasing elements, which a colony does not. A colony never invalidates pointers/iterators to elements unless the element being referred to is erased." The rest of the faq is here and I would appreciate it if people read it before casting judgement: http://www.plflib.org/colony.htm I am aware that it will be a lot of work to port colony to Boost, so I will only undertake this if there is genuine interest. In addition, plf::stack - which colony must use internally - is a std::stack equivalent container but with much better performance characteristics, which can be used outside of plf::colony. Asides from the performance characteristics, colonies have the following positive and negative properties: Positive: Lack of pointer/iterator invalidation makes interrelating between collections of data easier, without the cache misses associated with vectors of pointers to dynamically-allocated objects. Negative: Due to the additional overhead, performance can be worse for scalar types. Thanks in advance- Matt B

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[units] Conversions from quantities
by Michael Powell 14 Aug '15

14 Aug '15

Hello, Just wanted to clarify something. These should convert from given quantities to the desired units? double unit_conversion::from_length_to_inches(quantity<length> const & L) { const quantity<inch_base_unit::unit_type> result_(L); return result_.value(); } double unit_conversion::from_mass_to_pounds(quantity<mass> const & M) { const quantity<ounce_base_unit::unit_type> result_(M); return result_.value(); } >From an earlier post, I think maybe so, but I was interested in expert opinions, as well. https://groups.google.com/forum/#!topic/boost-list/YDJoMcu1Xx4 Thank you... Best regards, Michael Powell

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Boost 1.59.0 has been released
by Marshall Clow 13 Aug '15

13 Aug '15

Release 1.59.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains two new libraries and numerous enhancements and bug fixes for existing libraries. New Libraries * Convert: An extendible and configurable type-conversion framework, from Vladimir Batov. * Coroutine2: from Oliver Kowalke For details, including download links, see http://www.boost.org/users/news/version_1.59.0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.59.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Vladimir Prus Rene Rivera Marshall Clow Eric Niebler Daniel James Beman Dawes

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[Interprocess][Container] nested containers and scoped allocators
by Malko 13 Aug '15

13 Aug '15

Hi, First of all my setup: I am compiling on redhat 6 with clang 3.4 in C++03, using boost_1_58. In a project of mine I am using a map<int, vector<int>> (types to be stored in shared memory and I am using the proper allocators as per interprocess documentation). If mymap is an instance of such a type, then mymap[0] is an invalid syntax because of issues that, to the best of my understanding, are related to the fact that the map tries to use the default constructor (with the default allocator) for the nested type as operator[] also accounts for the case in which the entry is missing and must be constructed. Using at() instead of operator[] makes the whole thing compile. On construction, I give the usual instance of allocator<void, segment_manager> to mymap. According to what I read in Boost.Container docs: http://www.boost.org/doc/libs/1_58_0/doc/html/container/Cpp11_conformance.h… It would seem to me that a scoped allocator is a mechanism by which the allocator I gave to mymap is passed down to the nested vector. In which case I would expect operator[] to try to use such allocator instead of the default one. But then again, I always do mymap.insert(std::pair<const int, vector<int,...>>(0, vector<...>(my_void_alloc))) to add an element to the map, since I need to specify the allocator (and the examples in interprocess use this syntax). Given all of this, I would be grateful for any insight into the following: 1. If the scoped allocator is meant to be passed from the map to the vector, why can I not use operator[] and I necessarily need to use insert() to create a new vector in the map? Have I misunderstood what a scoped allocator is? Thanks in advance. -- View this message in context: http://boost.2283326.n4.nabble.com/Interprocess-Container-nested-containers… Sent from the Boost - Users mailing list archive at Nabble.com.

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1.59.0 rc3 is now available
by Marshall Clow 13 Aug '15

13 Aug '15

New Release candidate files for 1.59.0 are available at: http://boost.cowic.de/rc/ RC3 should fix the problem with VC14 and MSPDB140.DLL. As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: MD5 (boost_1_59_0_rc3.7z) = 0a2e512844f3e30a6240f8139ee983f3 MD5 (boost_1_59_0_rc3.tar.bz2) = 6aa9a5c6a4ca1016edd0ed1178e3cb87 MD5 (boost_1_59_0_rc3.tar.gz) = 51528a0e3b33d9e10aaa311d9eb451e3 MD5 (boost_1_59_0_rc3.zip) = 08d29a2d85db3ebc8c6fdfa3a1f2b83c Thanks! -- The release managers P.S. Release notes are here: http://www.boost.org/users/history/version_1_59_0.html

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[statechart] Events forwarding and orthogonal states
by lucaghera 13 Aug '15

13 Aug '15

Hi all, I've a problem similar to the one discussed in this old post: http://boost.2283326.n4.nabble.com/statechart-Broadcasting-events-to-orthog… I have a state, let's call it A, which contains two orthogonal regions. State X is the initial state of region 0 and state Y is the initial state of region 1. Both state A and state Y have a custom reaction for event E. State Y execute some computation based on event E while state A simply keeps track of how many times the event E is triggered. State A discard the event at the end of the custom reaction, while state Y forward it (the goal would be to forward it to the state A). >From the old post I think I have understood how the statechart library works and why the state Y never receives the event E. I guess that in my case state X is chosen as first state to process event E. Given that X is not interested in event E, the event is forwarded to state A, which process it and discard it. I see few possible solutions (with drawbacks) but I would like to know how this problem should be addressed. 1) I could do the counting directly in the state Y and remove the custom reaction to E from state A. This would work, however if tomorrow I will define a third state Z interested in E, I would have to duplicate the event counting code, which would work only if I assume that the Z and Y are not active at the same time (otherwise the event would be counted twice). 2) I could define an event that is listened only by state A and is triggered by the state Y after processing E. This doesn't seem really elegant and if multiple states are interested in E I have to be careful to not count the event twice. -- View this message in context: http://boost.2283326.n4.nabble.com/statechart-Events-forwarding-and-orthogo… Sent from the Boost - Users mailing list archive at Nabble.com.

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[variant] Possible regression from 1.55 to 1.58
by Mario Lang 12 Aug '15

12 Aug '15

Hi. I just upgraded my Boost from 1.55 to 1.58. My project doesn't build anymore, it fails on the following pattern, which used to work with 1.55: ---<snip>--- #include <algorithm> #include <boost/variant.hpp> #include <string> #include <iostream> #include <vector> struct visitor : boost::static_visitor<std::ostream &> { result_type operator() (int) { return std::cout; } result_type operator() (std::string) const { return std::cout; } }; int main() { std::vector< boost::variant<int, std::string> > v; visitor vis; foreach(v.begin(), v.end(), boost::apply_visitor(vis)); return 0; } ---<snip>--- The example is a bit silly, since foreach discards the return value of apply_visitor anyway. So my solution was to change the visitor to define result_type as void. This works. However, I am wondering why delayed_visitor does no longer work in this situation? Is it because I am trying to return a reference? -- CYa, ⡍⠁⠗⠊⠕

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Problem accessing boost trac
by Leo Carreon 12 Aug '15

12 Aug '15

Hi Boosters, Sorry to be posting this here but I’m trying to access boost trac and I’m getting a certificate error. Does anyone know how to resolve this issue? Regards, Leo

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[intrusive_ptr] Strange ternary op behavior with MSVC14
by TONGARI J 12 Aug '15

12 Aug '15

Hi, I found a strange bug while debugging: This is the minimal example that shows the problem: (the nullptr will be some other meaningful thing in real case) ```c++ #include <iostream> #include <boost/smart_ptr/intrusive_ptr.hpp> #include <boost/smart_ptr/intrusive_ref_counter.hpp> template<class T> struct wrapper { wrapper() = default; wrapper(boost::intrusive_ptr<T> const& p) : _p(p) {} boost::intrusive_ptr<T> const& get_ptr() const { #if 0 // This is OK. if (_p) return _p; return nullptr; #else // Strange behavior. return _p ? _p : nullptr; #endif } private: boost::intrusive_ptr<T> _p; }; struct W : boost::intrusive_ref_counter<W> { }; template<class T1, class T2> inline void test(wrapper<T1> const& s1, wrapper<T2> const& s2) { auto tup = std::make_tuple(s1.get_ptr(), s2.get_ptr()); std::cout << 0 << ":" << (void*)std::get<0>(tup).get() << "\n"; std::cout << 1 << ":" << (void*)std::get<1>(tup).get() << "\n"; } int main() { wrapper<W> a(new W), b(new W); test(a, b); return 0; } ``` If compiled with MSVC14, you'll see the 2 addresses are the same while they shouldn't. If if-stmt is used instead, the problem won't be shown. I also replaced intrusive_ptr with std::shared_ptr and the problem isn't shown as well. The same code works well with g++. It seems intrusive_ptr & MSVC14 specific but I can't reason about... Any idea?

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[Boost.ASIO] [asio] Scaling TCP Server
by Sarvagya Pant 11 Aug '15

11 Aug '15

I have created a TCP server that can receive two types of message from client. 1. "Heartbeat" : If this is found and "first_fetch" is 1, send some config in Json format else send {"config_changed" : "true"} 2. "Message" : If this is found, send {"success" : "true"} The async server is here => https://gist.github.com/mesarvagya/a73f2428417cb10336ef and the client is given here => https://gist.github.com/mesarvagya/90d764c749d18d9c5184 While both works fine, but the server is slower than expected. If one sees, I have used ~3kb message in client. When the client and server are connected, I did a preliminary benchmarking and the result were as follows: 1. For 50K messages, the time was 6 seconds. 2. For 100K messages, the time was 11 seconds. 3. For 200K messages, the time was 36 seconds. 3. For 500K messages, the time was 82 seconds 3. For 1million messages, the time was 174 seconds. The server is not working as expected. Currently it works at ~6K message/seconds in localhost. I would like to optimize the current server to receive at-least 100K messages per second. How should I begin with optimizing the server code? Is it possible to receive such high message/seconds in boost.ASIO and if so, how should I approach with the server design? -- *Sarvagya Pant* *Kathmandu, Nepal* *+9779803468257*

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building boost 1.54 thread
by W. Miah 11 Aug '15

11 Aug '15

Hello, I am having trouble building the threaded version of boost (version 1.54). I require version 1.54 only. I am getting the below error message. Any help will be greatly appreciated. Regards, Wadud. [root@bengal boost_1_54_0]# g++ --version g++ (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6) Copyright (C) 2014 Free Software Foundation, Inc. [root@bengal boost_1_54_0]# ./bootstrap.sh --prefix=/usr/local/boost-1.54 --with-libraries=thread Building Boost.Build engine with toolset gcc... tools/build/v2/engine/bin.linuxx86_64/b2 Unicode/ICU support for Boost.Regex?... /usr Generating Boost.Build configuration in project-config.jam... Bootstrapping is done. To build, run: ./b2 To adjust configuration, edit 'project-config.jam'. Further information: - Command line help: ./b2 --help - Getting started guide: http://www.boost.org/more/getting_started/unix-variants.html - Boost.Build documentation: http://www.boost.org/boost-build2/doc/html/index.html [root@bengal boost_1_54_0]# ./b2 install Component configuration: - atomic : not building - chrono : not building - context : not building - coroutine : not building - date_time : not building - exception : not building - filesystem : not building - graph : not building - graph_parallel : not building - iostreams : not building - locale : not building - log : not building - math : not building - mpi : not building - program_options : not building - python : not building - random : not building - regex : not building - serialization : not building - signals : not building - system : not building - test : not building - thread : building - timer : not building - wave : not building ...patience... ...patience... ...found 21612 targets... ...updating 38 targets... common.mkdir bin.v2 common.mkdir bin.v2/libs common.mkdir bin.v2/libs/system common.mkdir bin.v2/libs/system/build common.mkdir bin.v2/libs/system/build/gcc-4.9.2 common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi gcc.compile.c++ bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi/error_code.o In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:49: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ ./boost/cstdint.hpp:300:123: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:195: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ gcc.link.dll bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi/libboost_system.so.1.54.0 common.copy /usr/local/boost-1.54/lib/libboost_system.so.1.54.0 ln-UNIX /usr/local/boost-1.54/lib/libboost_system.so common.mkdir bin.v2/libs/thread common.mkdir bin.v2/libs/thread/build common.mkdir bin.v2/libs/thread/build/gcc-4.9.2 common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/detail/thread.hpp:29, from ./boost/thread/thread_only.hpp:22, from libs/thread/src/pthread/thread.cpp:11: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/thread.cpp:17: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ In file included from ./boost/system/system_error.hpp:14:0, from ./boost/thread/exceptions.hpp:22, from ./boost/thread/pthread/thread_data.hpp:10, from ./boost/thread/thread_only.hpp:17, from libs/thread/src/pthread/thread.cpp:11: ./boost/system/error_code.hpp:222:36: warning: ‘boost::system::posix_category’ defined but not used [-Wunused-variable] static const error_category & posix_category = generic_category(); ^ ./boost/system/error_code.hpp:223:36: warning: ‘boost::system::errno_ecat’ defined but not used [-Wunused-variable] static const error_category & errno_ecat = generic_category(); ^ ./boost/system/error_code.hpp:224:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable] static const error_category & native_ecat = system_category(); ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -fPIC -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/pthread/once_atomic.hpp:19, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -fPIC -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o" "libs/thread/src/pthread/once.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/future.o ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>libboost_thread.so.1.54.0 for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>pthread/thread.o... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.so.1.54.0 for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>libboost_thread.so.1.54.0... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.so for lack of <p/usr/local/boost-1.54/lib>libboost_thread.so.1.54.0... common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/link-static common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi gcc.compile.c++ bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi/error_code.o In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:49: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ ./boost/cstdint.hpp:300:123: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:195: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ gcc.archive bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi/libboost_system.a common.copy /usr/local/boost-1.54/lib/libboost_system.a common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/detail/thread.hpp:29, from ./boost/thread/thread_only.hpp:22, from libs/thread/src/pthread/thread.cpp:11: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/thread.cpp:17: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ In file included from ./boost/system/system_error.hpp:14:0, from ./boost/thread/exceptions.hpp:22, from ./boost/thread/pthread/thread_data.hpp:10, from ./boost/thread/thread_only.hpp:17, from libs/thread/src/pthread/thread.cpp:11: ./boost/system/error_code.hpp:222:36: warning: ‘boost::system::posix_category’ defined but not used [-Wunused-variable] static const error_category & posix_category = generic_category(); ^ ./boost/system/error_code.hpp:223:36: warning: ‘boost::system::errno_ecat’ defined but not used [-Wunused-variable] static const error_category & errno_ecat = generic_category(); ^ ./boost/system/error_code.hpp:224:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable] static const error_category & native_ecat = system_category(); ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/pthread/once_atomic.hpp:19, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o" "libs/thread/src/pthread/once.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/future.o ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a(clean) for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>pthread/thread.o... ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>pthread/thread.o... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.a for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a... ...failed updating 4 targets... ...skipped 6 targets... ...updated 28 targets... [root@bengal boost_1_54_0]#

1 0

Reusing expressions::stream
by Florian Lindner 11 Aug '15

11 Aug '15

Hello, with boost log I have: using namespace boost::log; add_file_log ( "sample.log", keywords::format = ( expressions::stream << expressions::format_date_time<boost::posix_time::ptime>("TimeStamp", "%H:%M:%S") << " [Rank: "<< expressions::attr<int>("Rank") << "]" << ": " << expressions::message ) ); which works fine. Now that may be a maximum stupid questions. But when I want to reuse the format expressions for other uses, e.g. another sink, how can I do that? i.e. how to declare and use a variable that holds that expressions? :-/ Thanks, Florian

1 0

Dijkstra Algorithm Implementation Details
by Mayank Bakshi 11 Aug '15

11 Aug '15

2 1

Install header-only libraries
by Gonzalo BG 11 Aug '15

11 Aug '15

I'm trying to find in the docs what is the right way to install only the header-only libraries from a boost distribution without any luck. That is, I want to install everything that can be installed without having to compile anything. Is there an argument for `bootstrap.sh` or `b2` that does this? Best regards, Gonzalo

2 3

[units] Dimensionless? expecting length+length
by Michael Powell 11 Aug '15

11 Aug '15

Hello, I am working on some trajectory calculations, and having a strange compiler error. First, great that I should get a compiler error at all! Second, what am I missing? quantity<acceleration> g() { static const auto gValue = static_cast<double>(9.812); static const auto metersPerSecondPerSecond = meters / second / second; static const quantity<acceleration> g = gValue*metersPerSecondPerSecond; return g; } double Class1::CalculateZeta(double timeMilliseconds, double heightMeters) { static const auto two = static_cast<double>(2); static const auto milliseconds = milli*seconds; const auto t = timeMilliseconds*milliseconds; const auto h = heightMeters*meters; const auto g_ = g(); auto result = -(g_ / two)*(t*t) + h; return result.value(); } Just if I did the dimensional analysis, I might expect the time components (i.e. T^2) to cancel themselves out, which should leave me with length+length, no? This is exposed via a C++ CLR (VS2013), but the Boost.Units are done internally. What am I missing here? I need to normalize the units, say to meters, etc? Best regards, Michael Powell Errors: Error 4 error C2676: binary '+' : 'boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::scale_list_dim<Scale>,boost::units::dimensionless_type>>>,void>,double>' does not define this operator or a conversion to a type acceptable to the predefined operator I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators Error 2 error C2784: 'add_typeof_helper<boost::units::unit<Dim1,System1,void>,boost::units::unit<Dim2,System2,void>>::type boost::units::operator +(const boost::units::unit<Dim1,System1,void> &,const boost::units::unit<Dim2,System2,void> &)' : could not deduce template argument for 'const boost::units::unit<Dim1,System1,void> &' from 'boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::scale_list_dim<Scale>,boost::units::dimensionless_type>>>,void>,double>' I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators Error 3 error C2893: Failed to specialize function template 'add_typeof_helper<boost::units::quantity<Unit1,X>,boost::units::quantity<Unit2,Y>>::type boost::units::operator +(const boost::units::quantity<Unit1,X> &,const boost::units::quantity<Unit2,Y> &)' I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators 5 IntelliSense: no operator "+" matches these operands operand types are: boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::list<boost::units::scale_list_dim<boost::units::scale<10L, boost::units::static_rational<-6L, 1L>>>, boost::units::dimensionless_type>>>, void>, double> + const boost::units::quantity<boost::units::unit<boost::units::length_dimension, boost::units::si::system, void>, double> i:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 49 Kingdom.Physics.Calculators

3 7

Weighted graph file for Dijkstra algorithm
by Mayank Bakshi 11 Aug '15

11 Aug '15

1 0

[units] Calculating air density
by Michael Powell 10 Aug '15

10 Aug '15

Hello, I'd like to calculate air density at altitude. Studying some notes on wikipedia: https://en.wikipedia.org/wiki/Density_of_air Symbol is typically Greek Rho, whose dimensions are generally M/L^3; units will probably be kg/m^3, although I am also reading about slugs/ft^3. Which incorporates a gas constant value: http://en.wikipedia.org/wiki/Gas_constant Whose units appear to be Joules/(Volume*Temp). I'm not seeing anything too terribly exotic there; all these units / dimensions are present in Boost.Units? As is usually the case, it is interesting to see how the units library "reduces" the units during code writing, compilation. Very impressive indeed. Thank you... Best regards, Michael Powell

1 4