November 2014 - Boost-users - lists.preview.boost.org

[boost::accumulators::impl::immediate_mean_impl<Sample, Tag>::operator()<Args>] c++/cli
by It neophyte 26 Nov '14

26 Nov '14

Hi While computing a variance on my dataset, I end up with: error C2677: binary '+' : no global operator found which takes type 'System::Object ^const ' (or there is no acceptable conversion) The error message point to the line 65 of mean.hpp (see below piece of code). Can someone explain what's going wrong? Thanks template<typename Args> // line 59 void operator ()(Args const &args) //line 60 { // line 61 std::size_t cnt = count(args); // line 62 this->mean = numeric::fdiv( // line 63 (this->mean * (cnt - 1)) + args[parameter::keyword<Tag>::get()] // line 64 , cnt // line 65 ); // line 66 } // line 67 my code: #pragma once#include "stdAfx.h"#include "math.h"#include <boost/accumulators/accumulators.hpp>#include <boost/accumulators/statistics/stats.hpp>#include <boost/accumulators/statistics/variance.hpp> ..... accumulator_set< double, stats<tag::variance> > acc_variance; DataRow^i; for (int i=1;i-1<dbdataset->Rows->Count-1;i++){ dbdataset->Rows[i-1]["DataRet"]=log(System::Convert::ToDouble(dbdataset- >Rows[i-1]["Pop"])/System::Convert::ToDouble(dbdataset->Rows[i]["Pop"])); acc_variance(dbdataset->Rows[i-1]["DataRet"]); lblvol->Text = Convert::ToString(sqrt(variance(acc_variance))); }

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boost::filesystem::extension crashes on Linux
by Jürgen Simon 26 Nov '14

26 Nov '14

Hello, I have a crash with boost 1.56 that happens on SUSE Linux for me (uname -a : Linux r105b.meteo.uni-bonn.de 3.7.10-1.28-desktop #1 SMP PREEMPT Mon Feb 3 14:11:15 UTC 2014 (c9a2c6c) x86_64 x86_64 x86_64 GNU/Linux) The crash happens in filesystem::extension() when listing a file from the following directory: $ ls -la core total 29802736 drwxr-xr-x 2 simon users 4096 Nov 25 14:40 . drwxr-xr-x 7 simon users 4096 Nov 25 15:05 .. -rw-r--r-- 1 simon users 30517985568 Nov 14 2013 rico.out.xy.core.nc As you can see there’s only one file in there that ends on “.nc”. The following code crashes on Linux but works fine on OSX (with the same data): fs::path f = fs::path(source_path); std::string extension = fs::extension(f); The GDB backtrace is: #0 0x00007fffe09403d5 in raise () from /lib64/libc.so.6 #1 0x00007fffe0941858 in abort () from /lib64/libc.so.6 #2 0x00007fffe11438cd in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib64/libstdc++.so.6 #3 0x00007fffe11419c6 in ?? () from /usr/lib64/libstdc++.so.6 #4 0x00007fffe11419f3 in std::terminate() () from /usr/lib64/libstdc++.so.6 #5 0x00007fffe1141c1e in __cxa_throw () from /usr/lib64/libstdc++.so.6 #6 0x00007fffe119336d in std::__throw_runtime_error(char const*) () from /usr/lib64/libstdc++.so.6 #7 0x00007fffe115e844 in std::locale::facet::_S_create_c_locale(__locale_struct*&, char const*, __locale_struct*) () from /usr/lib64/libstdc++.so.6 #8 0x00007fffe1153774 in std::locale::_Impl::_Impl(char const*, unsigned long) () from /usr/lib64/libstdc++.so.6 #9 0x00007fffe11547af in std::locale::locale(char const*) () from /usr/lib64/libstdc++.so.6 #10 0x00007ffff753036f in boost::filesystem::path::codecvt() () from /usr/local/lib/libboost_filesystem.so.1.55.0 #11 0x00007ffff75307ff in boost::filesystem::path::begin() const () from /usr/local/lib/libboost_filesystem.so.1.55.0 #12 0x00007ffff7530f88 in boost::filesystem::path::compare(boost::filesystem::path const&) const () from /usr/local/lib/libboost_filesystem.so.1.55.0 #13 0x00007ffff75310f4 in boost::filesystem::path::extension() const () from /usr/local/lib/libboost_filesystem.so.1.55.0 #14 0x0000000000448adb in boost::filesystem::extension (p=...) at /usr/local/include/boost/filesystem/convenience.hpp:36 Any ideas how to circumvent this problem? Jürgen

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[Boos-users][Boost.accumulators.Statistics.variance.hpp]: How to Compute Sample Volatility on data stored in DataTable
by It neophyte 26 Nov '14

26 Nov '14

Hi Do you know how can I compute a sample volatility of the returns held in a particular column of my db Datable? Any code illustration would be appreciated. Best,

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[accumulators->Statistics] How to Compute Sample Volatility_c++ Windows Form app
by It neophyte 25 Nov '14

25 Nov '14

Dear All Do you know how can I compute the sample volatility (sqrt(variance)) of the returns held in my Datable? For information, my db object contains a column "Return" which has been filled with values. DataTable^db=gcnew DataTable(); Thanks in advance Heron

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Re: [Boost-users] fusion: map
by MM 25 Nov '14

25 Nov '14

Hi, At the point of _defining_ a fusion::map, do the key types have to be known or can they just be forward declared at that point? Rds,

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Phoenix V2
by Mathieu Champlon 25 Nov '14

25 Nov '14

Hello, Has Phoenix V2 been removed from Boost 1.57 ? I used to be able to find it under boost/spirit/home/phoenix but it seems it's no longer the case. Thanks, MAT.

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Re: [Boost-users] lockfree::spsc_queue & move semantics
by Thomas Danckaert 24 Nov '14

24 Nov '14

From: Bjorn Reese <breese(a)mail1.stofanet.dk> Subject: Re: [Boost-users] lockfree::spsc_queue & move semantics Date: Mon, 10 Nov 2014 20:39:24 +0100 > On 11/09/2014 09:49 PM, Thomas Danckaert wrote: >> I'd like to use a spsc_queue of unique_ptr's to bigger objects, to >> transfer ownership between threads. That way, I can create/allocate an > > This limitation inherited from atomic, and I am afraid that it is a > bit more complicated than adding a move constructor. Fortunately, > there > is a C++ proposal to address the problem: > > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4058.pdf Is this really the issue here? What I'm trying to do is not the same as what's discussed in the proposal, as the reading/writing of the unique_ptr doesn't have to be an atomic operation in my case. I just want to push a unique_ptr onto the queue, and spsc_queue can store all kinds of objects, which are not atomic either. It only uses atomic operations to keep track of the write and read indices, and those parts of the code don't need to be modified to make this work. As far as I see, the main problem storing unique_ptr's (or any other non-copyable but moveable object), is that the code relies on a copy constructor to store objects in its internal buffer. I added an overload using a move constructor and that seems to work (though I'm quite new to multi-threading or lockfree programming, so I could be missing some potential issues). Thomas

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[Asio] null_buffers problem
by lin li 24 Nov '14

24 Nov '14

Hi, guys. I have some problem with null_buffers in Asio. According to the document, 'A null_buffers operation doesn't return until the I/O object is "ready" to perform the operation'. However, when I tried to use it in a asynchronous read, it keeps returning after all data has been received and the other end has closed the socket! So here is my questions: 1. what is "ready" exactly? 2. If we use null_buffers with async_read_some, will it detect some errors like disconnection and pass the error code to the completion handler?

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[serialization] Customizing serialization of boost::variant
by Elizabeta 22 Nov '14

22 Nov '14

Hi When serialization boost::variant, in the xml archive 'which' element is included that specify the number of the type that appears in the boost::variant at compile time. I need to include in the archive also the name of the type for debugging purpose . Anyone have idea how to do that -- View this message in context: http://boost.2283326.n4.nabble.com/serialization-Customizing-serialization-… Sent from the Boost - Users mailing list archive at Nabble.com.

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NT² 3.0 and Boost.SIMD - Stable release
by Joel Falcou 21 Nov '14

21 Nov '14

The first stable release of the 3.x series of MetaScale’s open-source software is available: NT² 3.0. It also includes its spin-off project, Boost.SIMD (not yet a Boost library). Many Issues have been closed since last beta. The main focus of this release cycle was to fix performances issues and to stabilize some parts of the API. Next step will be to separate NT2 and Boost.SIMD into separate repositories, thus making one more step toward Boost.SIMD submission into review. [ http://www.metascale.org/nt%C2%B2-3-0-and-boost-simd ] *Changes & Bug Fixes:* - Major performance improvements in both libraries - Added experimental support for the HPX runtime for parallelization on shared memory systems - Optimizations of many elemental functions, in particuler log/ex, frexp/ldexp and cbrt - More advanced shuffle pattern recognition for SIMD - Fixed issues with Visual Studio 2013 - More functions are force-inlined to ensure good performance - New functions for conversion between types and mixing of vectors of different sizes - Demo applications usable as benchmarks - Better handling of errors when an unsupported function is called - New API for custom memory allocators Full changelog is available at https://github.com/MetaScale/nt2/releases/tag/3.0.0. *How to get it ?* - Source and binary packages can be downloaded here: http://nt2.metascale.org/downloads - The release is also available on Github : https://github.com/MetaScale/nt2/releases - The main master branch is still under development : https://github.com/MetaScale/nt2

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