- Boost - lists.preview.boost.org

Re: [boost] [units] Pull request and RFC: information unit definitions for Boost.Units
by Curdeius Curdeius 27 Aug '14

27 Aug '14

Hi all, I have created a pull request building on top of Erik's proposal. It adds missing zebi and yobi prefixes as defined by IEC. I have also added tests for these prefixes. The only thing is that zebi (2^70) and yobi (2*80) are too large for *long long int*, so I test them with boost::multiprecision::int128_t. Link to PR: https://github.com/boostorg/units/pull/6 Description: I have added zebi and yobi IEC prefixes and corresponding tests for completeness taking Erik's pull request as a base. I am not sure if creating a new PR is a good solution or if there is any way to add a commit directly to the existing one. If you know a better way, I would appreciate any information. Regards, Marek Kurdej I would love to pass the responsibility for ongoing maintenance of > Boost.Units on to a new torchbearer. My time to dedicate to this project > has dwindled to essentially zero, and I believe it would be best for all > involved to enlist some fresh blood, ideally someone who is using the > library on a regular basis... Any volunteers? > As far as Erik's request, I don't have any objections to adding these to > the library, though I have not had time myself to verify that they are > correct. > Matthias > > > > > > ----- Original Message ----- > >> Link to PR: https://github.com/boostorg/units/pull/3 > >> > >> Description: > >> Adds unit definitions for standard units of information: bit, byte, > nat, > >> hartley, shannon. Defines a new unit system boost::units::information > for > >> convenient manipulation. Also includes IEC binary prefixes: kibi, mebi, > >> gibi, tebi, pebi, exbi > >> > >> Example code: > >> > https://github.com/erikerlandson/units/blob/info_units/example/information.… > > >> > >> Unit testing code: > >> > https://github.com/erikerlandson/units/blob/info_units/test/test_informatio… > > > > > > > > > I've been unable to raise a response from either Steven Watanabe or > Matthias Schabel, either on- or off-list. It would be nice to get a thumbs > up or thumbs down so I can make a decision on how to proceed with my other > project. >

5 7

Compile Time String in C++14
by TONGARI J 27 Aug '14

27 Aug '14

Hi all, I found a way to make CT strings in C++14, with the help of generic lambda. FYI, Ábel Sinkovics has presented a c++11 CT string in his mpllibs::metaparse[1] lib before, but it requires some PP trick which has a predefined limit MPLLIBS_LIMIT_STRING_SIZE. The new trick doesn't suffer from the limitation, but it assumes a null-terminated string. It's fairly simple, see below: ```c++ template<char...> struct str {}; template<char c> struct ch {}; template<int n> using idx = std::integral_constant<int, n>; template<class S, char c, char... cs> auto accum(S s, ch<c>, str<cs...>) { return accum(s, s(idx<sizeof...(cs) + 1>()), str<cs..., c>()); } template<class S, char... cs> auto accum(S, ch<0>, str<cs...> ret) { return ret; } template<class S> auto make_str(S s) { return accum(s, s(idx<0>()), str<>()); } #define LIT(s) make_str([](auto idx) { return ch<s[idx.value]>(); }) ``` Then you can use `doSomething(LIT("abc"))` in your code. What do you think? [1] http://abel.web.elte.hu/mpllibs/metaparse/

6 14

Re: [boost] [units] Interest in UDLs (e.g. _kg) for units?
by Marek Kurdej 27 Aug '14

27 Aug '14

> > From: Mathias Gaunard <mathias.gaunard(a)ens-lyon.org> > To: boost(a)lists.boost.org > Date: Mon, 25 Aug 2014 17:16:21 +0200 > Subject: Re: [boost] [units] Interest in UDLs (e.g. _kg) for units? > On 25/08/14 16:03, Sebastian Redl wrote: > > > > > > On 25 Aug 2014, at 13:24, Mathias Gaunard <mathias.gaunard(a)ens-lyon.org> > wrote: > > > >> On 22/08/14 10:08, Curdeius Curdeius wrote: > >>> > >>> Hi all, > >>> > >>> I was wondering if there is any interest in adding User-Defined > Literals > >>> (UDLs) to Boost.Units. > >>> > >>> IMO, it could simplify some code and improve code readability in some > cases. > >>> For example instead of writing (it's a somehow artificial example) > >>> 5.34 * si::milli * si::kilogram; > >>> 1234 * si::kilogram; > >>> one would write > >>> 5.34_g; > >>> 1234_kg; > >> > >> > >> Did you mean to write > >> 5.34_g * si::milli; > >> or > >> 5.34_mg; > >> ? > > > > > > No, to get grams you need si::milli * si::kilogram. I assume the > intention is that the _g suffix already includes that scaling - otherwise > it’d be broken. > > Sorry, I read that too fast. > In any case the idea would be to get suffixes that include all prefix > variants as well. Yes, the idea is to include all the prefix variants as well, so for the mass, we will have: ..., _ng, _ug (?), _mg, _g, _kg, _Mg,_Gg, _Tg, ... And, the fact is, writing si::milli * si::kilogram is counterintuitive as you have just experienced on your own. Marek Kurdej -- Ph.D. candidate

4 4

[endian][build] Boost build broken
by Marcel Raad 27 Aug '14

27 Aug '14

Hi, as mentioned on the Boost user mailing list a week ago (http://thread.gmane.org/gmane.comp.lib.boost.user/82429) I cannot build Boost from develop anymore. I just noticed that I can still build individual libraries, only the combination of Boost.System + Boost.Endian (and thus building all of Boost by just running "b2") is broken. "b2 --without-endian" works, "b2 --without- system" doesn't. Does anyone have any idea what the problem could be? The output of "b2 --with-system --with-endian" is: K:/boost/tools/build/src/build\virtual-target.jam:1099: in virtual- target.register-actual-name from module virtual-target error: Duplicate name of actual target: <pstage\lib>libboost_system-vc140- mt-gd-1_57.lib error: previous virtual target { common%common.copy-libboost_system-vc140- mt-gd-1_57.lib.STATIC_LIB { msvc%msvc.archive-libboost_system-vc140-mt-gd -1_57.lib.STATIC_LIB { msvc%msvc.compile.c++-error_code.obj.OBJ { error_code.cpp.CPP } } } } error: created from ./stage-proper error: another virtual target { common%common.copy-libboost_system-vc140-mt- gd-1_57.lib.STATIC_LIB { msvc%msvc.archive-libboost_system-vc140-mt-gd- 1_57.lib.STATIC_LIB { msvc%msvc.compile.c++-error_code.obj.OBJ { error_code.cpp.CPP } } } } error: created from ./stage-proper error: added properties: <asynch-exceptions>off <warnings>on error: removed properties: <asynch-exceptions>on <warnings>all K:/boost/tools/build/src/build\virtual-target.jam:484: in actualize-no- scanner from module object(file-target)@3811 K:/boost/tools/build/src/build\virtual-target.jam:134: in class@virtual- target.actualize from module object(file-target)@3811 K:/boost/tools/build/src\build-system.jam:720: in load from module build- system K:\boost\tools\build\src/kernel\modules.jam:289: in import from module modules K:\boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build from module K:\boost\boost-build.jam:17: in module scope from module

2 4

[Graph] 'traverse' event in DFS visitor concept?
by Jeremy Murphy 27 Aug '14

27 Aug '14

I have been trying to figure out how to use the dfs_visitor to do something every time a vertex is 'traversed', which would be (num_children(v) + 1) times for any given vertex v, for a total of (2n - 1) traversals on a graph of size n. (I have been working on rooted trees, so the application to general graphs may be a bit rough.) The use case is calculation of Eulerian paths, which I occasionally see people asking how to do. So although the dfs_visitor doesn't support this notion of 'traverse', I have been able to simulate it using tree_edge and finish_vertex and some post-processing. If you let "result" be an output iterator in a dfs visitor class with these member functions: template <typename Edge, typename Graph> void tree_edge(Edge const &e, Graph const &g) { *result++ = boost::source(e, g); *result++ = boost::target(e, g); } template <typename Vertex, typename Graph> void finish_vertex(Vertex const &v, Graph const &) { *result++ = v; } Then apply std::unique to the resulting sequence to remove adjacent duplicates, the result is an Eulerian circuit (if one is possible). (Alternatively you could check for duplicate values at time of traversal.) So apart from showing a simple way to calculate Eulerian path/circuit, I wanted to suggest: is it worth adding a 'traverse/visit' event to dfs (or bfs) visitor concept for this kind of use case? It would sure reduce the computation (though not the complexity) required in this case. Cheers. Jeremy

2 3

[graph] strong_components & depth_first_visit feature proposal
by Alexander Lauser 27 Aug '14

27 Aug '14

Hi all, I am writing two minor extensions for Boost.Graph, making strong_components and depth_first_visit more generic. This mail is to assess interest in publishing these features. * Question 1: What about extending strong_components to allow the user to (optionally) hook into DFS-events? The rationale for that is that when computing strong components, one may also be interested in connecting paths between any two distinct vertices in a component. With the ability to hook into the events, the paths can be traced, using tree_edge and back_edge to store paths to/fro the root of the component. One may possibly even allow additional events with respect to the discovery and finishing of components as well as the adding of vertices. What do you think about that? A technical question w.r.t the implementation of such a visitor: Why is the name dispatching for the named parameters of strong_components done "by hand" and not using the same facilities as depth_first_search? (I'm quite new to Boost and most of its notions like named parameters, so I may have missed something trivial. If so I beg to forgive the question.) * Question 2: What about introducing a new (optional) event for finish_tree_edge during a depth_first_visit? This event would be called when backtracking a tree_edge. Even though I cannot give a specific application where such an event would be essential, I still think it's a event during a depth-first-search that is natural enough to allow the user to hook in. (N.b. that similar events finish_back_edge and finish_forward_or_cross_edge would not make sense as they get always called immediately after back_edge and forward_or_cross_edge, respectively.) * Another minor question: Why are not all events of a DFS-visitor optional (like finish_edge is)? I think this would make implementing a partial DFS-visitors easier (by not having to derive from dfs_visitor in order to provide events that one is not interested in). A problem in the implementation of this would be that there is currently a bug (ticket 10231) with the current implementation that makes finish_edge optional. - Alex

2 2

[build] Running b2 with particular toolset invokes other toolsets in user-config.jam
by Edward Diener 27 Aug '14

27 Aug '14

I brought up this issue on the Boost build mailing list and it was eventually ignored, so I will bring it up here again. If I run "b2 toolset=sometoolset" Boost Build ends up invoking other toolsets in my user-config.jam along with "sometoolset" to do the build. This invoking of other toolsets seems not only a waste of time and unnecessary but also wrong in the sense that the invoking of some other toolset in user-config.jam may produce an error. I do not understand the necessity for invoking other toolsets in user-config.jam when I have specified the toolset I want. The practical situation for me which is causing problems with Boost Build behavior, because of the actions described above, is that I have a local setup under Windows where I can run many different versions of gcc/mingw or gcc/mingw64. In order to do this I using a changing symbolic link, on my PATH, to point to any one of many versions of gcc in different directories. I have a file running appropriate commands that switches between the versions. I have also built clang on Windows with a particular gcc version and therefore any invocation of clang looks for the run-time system of that particular version when clang is invoked. So if I "switch" gcc to a version which is not the one wih which i built clang, and then invoke Boost Build with that gcc toolset, clang also gets invoked as explained in the beginning remarks above, and this gives an error from the clang invocation. It is true that Boost Build continues, even after the error message coming from clang, in executing the appropriate jamfile with the particular version of gcc as the toolset. But it is annoying nonetheless to see this error for a toolset I am not even invoking. Cannot something be done in Boost Build so that if I am invoking toolset=x there should be no reason to be trying toolset=y unless it is actually needed for something when using toolset=x ? As for instance when the bjam files specifies some other tool ( doxygen, fop, xsl ) which have to be used.

2 4

[documentation] Incorrect link in prebuilt Win binaries.
by Mostafa 26 Aug '14

26 Aug '14

1) Download and install boost_1_56_0-msvc-8.0-64 2) Open libs/libraries.htm 3) Click the link for static_assert 4) Wrong 2nd link in the following message: Automatic redirection failed, please go to ../../doc/html/boost_staticassert.html or view the online version at http://www.boost.org/regression-logs/cs-win32_metacomm/doc/html/boost_stati…

1 0

Building boost on osx 10.9 mavericks
by Jerome Laurens 26 Aug '14

26 Aug '14

Hi I could build boost 1.56 on macosx 10.9 for 10.9 but I do not manage to build boost on macosx 10.9 targeting macosx 10.8. It seems that darwin.jam does not recognize the installed SDKs such that I cannot use macosx-version feature. Now the developer resources are no longer in the /Developer folder but in /Applications/.../Xcode.app/Contents/Developer I tried to symlink this folder from /, I also tried a root=... argument to no avail. Any hint ? Tia Jérôme LAURENS

1 0

Movable but not copyable bug?
by Mostafa 26 Aug '14

26 Aug '14

I had posted this on the user's list but I think this should be brought to the attention of the developers. The following code contains a templated copy constructible Boost.Move enabled class (Bar) with a single non-copy constructible Boost.Enabled member (Foo). If Bar's copy constructor is not explicitly defined then the code compiles with both g++ 4.8.2 and VS2005, else if it's explicitly defined then it fails to compile on g++ 4.8.2 I think this is due to the fact that g++ 4.8.2 erroneously instantiates Bar's default copy constructor in the latter case. Is this a Boost.Move bug or a gcc bug? #include <boost/move/core.hpp> #include <boost/move/utility.hpp> struct Foo { Foo(int x, int y) {} Foo(BOOST_RV_REF(Foo) rhs) {} private: //Purposefully declared and not defined. Foo & operator=(Foo); private: BOOST_MOVABLE_BUT_NOT_COPYABLE(Foo) }; template <typename T> struct Bar { Bar() : f(0, 1) {} // (1) //Bar(Bar const & rhs) //: f(rhs.f) //{} Bar(BOOST_RV_REF(Bar) rhs) : f(::boost::move(rhs.f)) {} private: //Purposefully declared and not defined. Bar & operator=(Bar); private: BOOST_COPYABLE_AND_MOVABLE(Bar) private: T f; }; Foo f1() { return Foo(0, 1); } Bar<Foo> f2() { return Bar<Foo>(); } int main() { // Foo f( f1() ); Bar<Foo> b(( Bar<Foo>() )); // Bar<Foo> b1; // Bar<Foo> b2(b1); return 0; }

4 14

[Range] compilation error with mfc-iteration-support
by Tobias Loew 26 Aug '14

26 Aug '14

Hi, moving parts of range_const_iterator to the namespace range_detail in file boost/range/const_iterator.hpp leads to ambiguity in /range/detail/mfc.hpp line 747: 25>..\src\libs\boost\boost\boost/range/mfc.hpp(747): error C2872: 'range_const_iterator' : ambiguous symbol 25> could be '..\src\libs\boost\boost\boost/range/const_iterator.hpp(67) : boost::range_const_iterator' 25> or '..\src\libs\boost\boost\boost/range/const_iterator.hpp(40) : boost::range_detail::range_const_iterator' 25> ..\src\libs\boost\boost\boost/range/detail/microsoft.hpp(135) : see reference to class template instantiation 'boost::range_detail_microsoft::customization<Tag>::meta<X>' being compiled 25> with 25> [ 25> Tag=CEbsValueArray::mfc_range_base_type, 25> X=CTypedPtrArray<CObArray,EbsValue *> 25> ] 25> ..\src\libs\boost\boost\boost/range/begin.hpp(111) : see reference to class template instantiation 'boost::range_detail_microsoft::const_iterator_of<T>' being compiled 25> with 25> [ 25> T=CTypedPtrArray<CObArray,EbsValue *> 25> ] ... changing the name of boost::range_detail::range_const_iterator to boost::range_detail::range_const_iterator_helper resolves the problem. I expect other begin/end adapters to run into the same problem. Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/Range-compilation-error-with-mfc-iterati… Sent from the Boost - Dev mailing list archive at Nabble.com.

2 2

[endian] Boost.Endian library added for 1.57.0
by Beman Dawes 26 Aug '14

26 Aug '14

The library provides integer and floating point types and conversion functions for portable byte ordering regardless of processor endianness. Although the primary uses are for file or network I/O, it is also useful for unaligned integers or floats, or for 3, 5, 6, and 7 byte integers. The library's predecessors have been in use for thirty years and developed independently multiple times. The repository is https://github.com/boostorg/endian The documentation is online at https://boostorg.github.io/endian/ See https://boostorg.github.io/endian/index.html#Release-history for changes since the Formal Review. No need to report "Inspection Report" problems; those will be cleaned up before 1.57.0 ships. Please do report any other problems or concerns, since the time between now and when the 1.57.0 beta ships in effect acts a mini-review period. If anyone has access to a big-endian platform with a modern C++ compiler, please, please run the endian test suite and report the results. All testing and use in recent years has been on little-endian platforms, so big-endian platform testing is a worry. Thanks for you patience, --Beman

7 9

Align and TypeIndex are missing in components list
by Antony Polukhin 25 Aug '14

25 Aug '14

Hi, It is impossible to create a ticket for TypeIndex or Align libraries in track (https://svn.boost.org/trac/boost/newticket) -- Best regards, Antony Polukhin

2 1

[Serialization] link error in 1.56
by Tobias Loew 25 Aug '14

25 Aug '14

Hi, linking the serialization lib fails in version1.56 with unresolved symbols due to the missing implementation of boost::archive::detail::shared_ptr_helper::shared_ptr_helper(void) boost::archive::detail::shared_ptr_helper::~shared_ptr_helper(void) up to version 1.55 those symbols were defined in libs\serialization\src\shared_ptr_helper.cpp, but now this file is excluded from the build and contains the implementation of a nowhere defined class shared_ptr_helper_base. Is there a replacement for shared_ptr_helper, is it redundant or is serialization broken in 1.56? Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/Serialization-link-error-in-1-56-tp46668… Sent from the Boost - Dev mailing list archive at Nabble.com.

2 2

[container] New container: why is everybody silent?
by Alexander Kuprijanov 25 Aug '14

25 Aug '14

Hi boost community! Please tell me something about my container, don't be silent. I firmly intend to offer it to boost, because it's much faster than competitors (by a constant factor). It's intended to replace std::vector in cases, when an application requires multiple insertion/deletion. It takes O(log(N)) for insertion/deletion. Docs: http://alexkupri.github.com/array/ Code: https://github.com/alexkupri/array Best regards, Aleksandr Kupriianov

10 22

[move] const rvalue failure.
by Mostafa 25 Aug '14

25 Aug '14

The following fails to compile on both g++ 4.8.2 and VS2005 using Boost 1.56: #include <boost/move/core.hpp> #include <boost/move/utility.hpp> struct MOC { MOC() : value(121) {} MOC(BOOST_RV_REF(MOC) rhs) : value(rhs.value) {} int value; private: //Declared and purposefully not defined. MOC & operator=(MOC); private: BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) }; MOC moveonlyMutableRValue() { return MOC(); } MOC const moveonlyConstRValue() { return MOC(); } int main() { MOC m(moveonlyConstRValue()); return 0; } with g++, I get the following error messages: boost_move_const_rvalue.cc: In function ‘int main()’: boost_move_const_rvalue.cc:28:30: error: invalid user-defined conversion from ‘const MOC’ to ‘boost::rv<MOC>&’ [-fpermissive] MOC m(moveonlyConstRValue()); ^ In file included from boost_move_const_rvalue.cc:1:0: /home/HPC/boost_installed/v1_56_0/include/boost/move/core.hpp:219:7: note: candidate is: MOC::operator boost::rv<MOC>&() <near match> operator ::boost::rv<TYPE>&() \ ^ boost_move_const_rvalue.cc:13:3: note: in expansion of macro ‘BOOST_MOVABLE_BUT_NOT_COPYABLE’ BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) ^ /home/HPC/boost_installed/v1_56_0/include/boost/move/core.hpp:219:7: note: no known conversion for implicit ‘this’ parameter from ‘const MOC*’ to ‘MOC*’ operator ::boost::rv<TYPE>&() \ ^ boost_move_const_rvalue.cc:13:3: note: in expansion of macro ‘BOOST_MOVABLE_BUT_NOT_COPYABLE’ BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) ^ boost_move_const_rvalue.cc:28:30: error: passing ‘const MOC’ as ‘this’ argument of ‘MOC::operator boost::rv<MOC>&()’ discards qualifiers [-fpermissive] MOC m(moveonlyConstRValue());

1 2

[serialization] get_helper documentation
by Joaquin M Lopez Munoz 24 Aug '14

24 Aug '14

Hi, I see the Loading and Saving Archive concepts in Boost.Serialization have been augmented with helper support via get_helper<Helper>(). However, this is only explicitly documented for *Loading* Archives, http://www.boost.org/libs/serialization/doc/archives.html when indeed Saving Archives must and do also provide such a member function. Best, Joaquín M López Muñoz Telefónica

1 0

[type_traits] is_character<T> trait
by Antony Polukhin 24 Aug '14

24 Aug '14

Hi, Boost.LexicalCast has a trait boost::detail::is_character<T>, that evaluates to true if T is char, char16_t, wchar_t, unsigned char or any other character type. If this trait looks useful, I can move it to TypeTraits library, add docs and tests. Is there any interest in such trait? -- Best regards, Antony Polukhin

3 2

Re: [boost] [Boost-users] [Chrono] The default BOOST_CHRONO_VERSION is still 1
by Vicente J. Botet Escriba 24 Aug '14

24 Aug '14

Le 24/08/14 01:49, DonM a écrit : > -------- Original Message -------- > Subject: Re: [Boost-users] [Chrono] The default BOOST_CHRONO_VERSION > is still 1 > From: "Vicente J. Botet Escriba" <vicente.botet(a)wanadoo.fr> > Date: 8/23/2014 6:28 AM > To: boost-users(a)lists.boost.org >> >> Le 23/08/14 01:41, DonM a écrit : >>> The docs (boost_1_56_0/doc/html/chrono/reference.html) say: >>> >>> "The default value for BOOST_CHRONO_VERSION will be changed to 2 >>> since Boost 1.55. " >>> >>> However, it still has the value 1 in both 1.55 and 1.56. >>> >>> Not a big deal, I just noticed and figured I'd mention it. >>> >> Hi, >> >> I must remove this comment as as there is a incompatibility this will >> break user code. I planned to do a smooth trarnsition, but there were >> some complains. >> >> Thanks for pointing this issue, >> Vicente > > Are you saying that you never intend to change the default value? That > would be a mistake, in my opinion. Version 2 is much better -- the I/O > stuff works. If users need backwards compatibility, they can define > version 1, but encourage people to use version 2. Just my $0.02. > What others think? Vicente

1 0

[math] pull request for boost::math::round bug in corner cases
by Robin Eckert 24 Aug '14

24 Aug '14

Hello, I found two corner cases in which boost::math::round doesn't round correctly. For double types, these are the numbers directly beneath 0.5: +/- 0.499999999999999944488848768742172978818416595458984375 (which get rounded to 1.0 although their aboslute value is smaller than 0.59) and odd integral numbers on the edge of the mantissa length: +/- 4503599627370497.0 +/- 4503599627370499.0 +/- 4503599627370501.0 ... +/- 9007199254740989.0 +/- 9007199254740991.0 +/- 9007199254740993.0 These get rounded to the next bigger/smaller integral value. For a detailed explanation and a fix, see the description of the pull request on https://github.com/boostorg/math/pull/8 Regards, Robin

1 0

[test] Using BOOST_CHECK_EQUAL with enum
by Edward Diener 23 Aug '14

23 Aug '14

In code I have the expression: BOOST_CHECK_EQUAL(cnew,e_test_third); where 'cnew' is: test_enum cnew; and test_enum is: enum test_enum { e_test_default, e_test_first, e_test_second, e_test_third }; This is giving me the error: ..\..\../boost/test/test_tools.hpp:100:1: error: expected ')' before 'do' do { \ ^ ..\..\../boost/test/test_tools.hpp:169:5: note: in expansion of macro 'BOOST_CHECK_WITH_ARGS_IMPL' BOOST_CHECK_WITH_ARGS_IMPL( ::boost::test_tools::tt_detail::equal_impl_frwd(), "", CHECK, CHECK_EQUAL, (L)(R) ) ^ test_auto_value.cpp:64:4: note: in expansion of macro 'BOOST_CHECK_EQUAL' BOOST_CHECK_EQUAL(cnew,e_test_third); ^ Is Boost Test incapable of checking that an enumeration object equals an enumerated value ? Is this a known problem ? How do I work around it ?

1 1

[iterator] Merge pull request
by Andrey Semashev 23 Aug '14

23 Aug '14

Hi, Some time ago I made this pull request: https://github.com/boostorg/iterator/pull/6 It makes some of the implementation details of Boost.Iterator public. These components are already used in Boost.Range and Boost.Tokenizer and the intent is to further patch these libs to use public interfaces instead of the implementation details. Could this pull request be merged?

2 6

[filesystem] Epoch of trivial_clock
by Bjorn Reese 23 Aug '14

23 Aug '14

The filesystem::trivial_clock type is implementation-defined [1]. That means that the epoch is also implementation-defined. How do we determine the epoch of trivial_clock? For instance, we may need to represent the last_write_time() timestamp to the end-user, or transfer it to another node when we implement a network file system. PS: I am looking at the std::filesystem proposal, but I assume that boost::filesystem will be update accordingly. [1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4097.html#8

5 7

GSOC: Boost.Math: hypergeometric functions
by Anton Bikineev 22 Aug '14

22 Aug '14

Hi all, I'm glad to represent my GSoC project work about implementation of hypergeometric functions: https://github.com/BoostGSoC14/boost.math I would like to thank everybody who helped me, essentially my mentor Christopher Kormanyos, my advisors John Maddock, Paul Bristow and, of course, Niall Douglas. The concentration of the project was mostly confluent hypergeometric function 1f1. Some essential algorithms were implemented and research works were done. A few short articles may be read in my blog: http://antoha-bikineev.blogspot.com Of course, it's gonna be updated while researching. The most important thing for me is that this work opened new ideas, ways and approaches for development and investigation of new numerical algorithms. Some of them are intended to reduce probability of cancellation errors in power series and to reduce round-off errors for recurrence relations at unstable directions. So there are plenty of stuff to do and improve.

1 0

[graph] Faster strong_components-implementation
by Alexander Lauser 22 Aug '14

22 Aug '14

Hi all, reimplementing Tarjan's dfs-visitor used in Boost.Graph's algorithm to compute strong components yielded a performance gain of about 15 to 20% (for adjacency_list-graphs). The problem is that due to bug #10231 [1], this implementation does not work with a current vanilla version of Boost. (See below for some details explaining my changes and the reason it is affected by the bug.) Is there interest in the faster implementation? If so, what's the best way to proceed? Wait until the bug is fixed and then incorporate the changes in a pull request? Create a pull request and hope that is not merged before the bug is fixed? Btw, my feeling is that the bug's not too involved and I tried to fix it myself. It seems that it is not even in Boost.Graph itself, but in Boost.TTI (in the macro-depths of which I got lost). Should I file a separate bug for Boost.TTI? For the details: My implementation is a back-to-the-root-approach, following the classical formulations of Tarjan's algorithm more closely. The current implementation somewhat "simulates" edge events upon leaving a vertex by an additional loop over all edges incident to the vertex. This can be avoided by using finish_edge -- which suffers from the above mentioned bug. (In addition to the performance-boost, I think it is also more natural to implement Tarjan's algorithm using finish_edge.) Cheers, Alex [1] https://svn.boost.org/trac/boost/ticket/10231

1 0