August 2021 - Boost-users - lists.preview.boost.org

Boost Installation in Codeblocks
by Alexander Tanseco 17 Aug '21

17 Aug '21

I successfully built Boost in my directory c:\boost_1_77_0. After which, I set up my global variable boost with base c:\boost_1_77_0. For the built-in field lib, I entered c:\boost_1_77_0\stage\lib (see attached screenshot). For the program's build options, under Linker settings/Link libraries: $(#boost.stage.lib) Under Search Directories/Compiler I entered $(#boost) and under Search Directories/Linker I entered $(#boost.stage.lib). When I built a typical Hello World program (see attached screenshot), I get an error message (see attached screenshot). Where did I go wrong? Somebody, please help.

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[release]Boost 1.77.0
by Marshall Clow 14 Aug '21

14 Aug '21

Release 1.77.0 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. * Describe: A C++14 reflection library, from Peter Dimov. Provides macros for describing enumerators and struct/class members, and primitives for querying this information. * Lambda2: A C++14, dependency-free, single header lambda library, from Peter Dimov. For details, including download links, see <http://www.boost.org/users/news/version_1.77.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.77.0/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. Thanks, -- The Boost Release Team Marshall Clow, Michael Caisse, Glen Fernandes

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Replace icpx with icpc
by Borchert, Christopher B ERDC-RDE-ITL-MS CIV 10 Aug '21

10 Aug '21

I'm trying to build Boost 1.76 from source on SLES 15 using Intel 19.1.3.304 (and GCC 10.2.0 underneath). Simply, how to I get b2 not to use icpx? With icpc it builds but icpx gives ./b2 toolset=intel-linux icpx: error while loading shared libraries: libimf.so: cannot open shared object file: No such file or directory I've tried everything and resorted to altering $PATH to remove icpx, which is how I know that's the problem. Thanks, Chris

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[boost][multiprecision/mpc][math/quadrature] Why boost::multiprecision::exp gets stuck when evaluating complex-valued integral?
by Kirill Kudashkin 06 Aug '21

06 Aug '21

Dear all, I have encountered a problem while using Boost C++ libraries ( multiprecision/mpc.hpp, math/quadrature) which I cannot resolve. This problems appears when running the following piece of code || |#include <boost/math/constants/constants.hpp> #include <boost/math/quadrature/exp_sinh.hpp> #include <boost/multiprecision/mpc.hpp> #include <boost/multiprecision/mpfr.hpp> #include <boost/math/special_functions/fpclassify.hpp> namespace mpns = boost::multiprecision; typedef mpns::number<boost::multiprecision::mpc_complex_backend <50> > mpc_type ; typedef mpc_type::value_type mp_type ; int main() { using boost::math::constants::root_pi ; mpc_type z{mp_type(1),mp_type(1)} ; auto f = [&](mp_type x) { //actually I did not test if all these conditions are needed... if (boost::math::fpclassify<mp_type> (x) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mp_type x2 = mpns::pow(x,2U) ; if (boost::math::fpclassify<mp_type> (x2) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x2) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mpc_type ex2 = mpns::exp(-z*x2) ; if (boost::math::fpclassify<mpc_type> (ex2) == FP_ZERO) { return mpc_type(mp_type(0)) ; }; return ex2 ; } ; mp_type termination = boost::math::tools::root_epsilon <mp_type> () ; mp_type error; mp_type L1; size_t max_halvings = 12; boost::math::quadrature::exp_sinh<mp_type> integrator(max_halvings) ; mpc_type res = integrator.integrate(f,termination,&error,&L1) ; mpc_type div = 2U*mpns::sqrt(z) ; mpc_type result = (mpc_type(root_pi<mp_type> ())/div) - res ; return 0; } | ||Namely, the problem appears when evaluating the exponent. The code is compiled without any problems, but hangs on computing | mpc_type ex2 = mpns::exp(-z*x2) ;| It was possible to go into the function while debugging. It crashed eventually, when the compiler reached "unable to resolve non-existing file.../src/init2.c". I let it run for a while checking the call stack. It appears that the programs is stuck atcalling ___gmpn_sub_n_coreisbr(). Or better, in the call stuck it appeared frequently. I did several tests. The real-valued version (with mpfr_backend <2000>) works without any problems. cpp_complex_backend <100> works fine, but I could not test higher precision yet, since it is much slower. I found a work-around which is not ideal. Namely, mpc_type ex2 = mpc_type(mpns::exp(x2)) ; mpc_type ezx2 = mpns::pow(ex2,-z) ; works fine with mpc_complex_backend <2000>. The lambda-function as it is declared in the code above works and yields correct numbers. The problem appears when it is called from the integrator. My system. I use openSUSE Tumbeleweed. I installed boost libraries as provided by |boost_1_76_0-gnu-mpich-hpc-devel.| Complier -> g++, cppStandard gnu+17. I check that I have all libs, e.g. libgmp, libmpc, libmpfr and etc. All headers are present (the programs is complied without any warnings). Thank you in advance and Best wishes, Kirill ||

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[release] Boost 1.77.0 Release Candidate 1
by Marshall Clow 06 Aug '21

06 Aug '21

The first release candidates for the 1.77.0 release are now available at: <https://boostorg.jfrog.io/artifactory/main/release/1.77.0/source/> The SHA256 checksums are as follows: fc9f85fc030e233142908241af7a846e60630aa7388de9a5fafb1f3a26840854 boost_1_77_0_rc1.tar.bz2 f2dd9722b21450daf5ce8ef82c2d99c7ec304f913ee6c6b7f047d5639503dda1 boost_1_77_0_rc1.7z 5347464af5b14ac54bb945dc68f1dd7c56f0dad7262816b956138fc53bcc0131 boost_1_77_0_rc1.tar.gz d2886ceff60c35fc6dc9120e8faa960c1e9535f2d7ce447469eae9836110ea77 boost_1_77_0_rc1.zip 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. -- The Release managers

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Boost multiprecision as array index
by Claudio La Rosa 03 Aug '21

03 Aug '21

Hi to all, I unsuccessfully tried to use a boost multiprecision variable (object?) as index of an array. Int myArray[100]; uint128_t index = 23; int value = myArray[index]; This code don’t work. There is a way for to use a multiprecision as index of an array? Thanks. Claudio La Rosa

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[Boost.Json] Loss of precision during serialization/parsing plain double ?
by Marc Viala 03 Aug '21

03 Aug '21

Hello Boost users, I'm starting to implement some serialization tools with Boost.Json but I've got some precision issues with double values. To demonstrate this "potential" issue, you will find here after a code snippet to reproduce it: #include <boost/json.hpp> BOOST_AUTO_TEST_CASE(bjson_double_serialize_ut) { namespace bjs = boost::json; static double ref_values[] = { 1217.2772861138403 , -161.68713249779881 , 267.04251495962637}; std::string s; { const bjs::value jv = { ref_values[0] , ref_values[1], ref_values[2], 0.0, 0.0, 0.0}; s = serialize(jv); } double values[3] = {}; { const auto jv{bjs::parse(s)}; values[0] = jv.as_array().at(0).as_double(); values[1] = jv.as_array().at(1).as_double(); values[2] = jv.as_array().at(2).as_double(); } static constexpr auto eps{std::numeric_limits<double>::epsilon()}; BOOST_TEST(std::abs(ref_values[0] - values[0]) <= eps); BOOST_TEST(std::abs(ref_values[1] - values[1]) <= eps); BOOST_TEST(std::abs(ref_values[2] - values[2]) <= eps); } When I compiling and running this code w/ Boost 1.75 and Microsoft Visual C++ version 14.2 (VS 2019) / Windows 10, I've got the following output: "bjson_double_serialize_ut": check std::abs(ref_values[0] - values[0]) <= eps has failed [2.2737367544323206e-13 > 2.2204460492503131e-16] "bjson_double_serialize_ut": check std::abs(ref_values[2] - values[2]) <= eps has failed [5.6843418860808015e-14 > 2.2204460492503131e-16] >From my point of view, I'm expecting to get a tolerance equal or inf. to my "double machine epsilon". Is this correct and how can I address it ? Marc -- Marc Viala

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