September 2012 - Boost-users - lists.preview.boost.org

[reminder] [Review] ODEInt review ends tomorrow September 28
by Steven Watanabe 27 Sep '12

27 Sep '12

AMDG The review of Karsten Ahnert and Mario Mulansky's ODEInt library will end tomorrow. Only a few reviews have been submitted so far. If you plan to submit a review, please let me know. If anyone needs more time, we can see about extending the review period. -------------------------------------- About the library: odeint provides routines for numerically solving Ordinary Differential Equations, a task heavily required when approaching scientific problems numerically. In odeint we have implemented the most common algorithms in a modern, generic way which provides several advantages over existing implementations. The main focus of odeint is to separate algorithms from the underlying basic computation unit. This allows for example to easily use the power of modern GPUs via CUDA or OpenCL to speed up computational heavy simulations. Features: - provides most of the standard algorithms, including step size control, dense ouput and extrapolation routines - symplectic routines for Hamiltonian systems - implicit routines based on boost::ublas (MTL4 in progress) - high level integrate functions - interchangeable computation backend with existing bindings to CUDA and OpenCL - native support of ODEs defined for complex values - support of Boost.Units in most of the algorithms - support of arbitrary precision types You can download the library and view the documentation here: zip: http://github.com/headmyshoulder/odeint-v2/zipball/master github: http://headmyshoulder.github.com/odeint-v2/ docs: http://headmyshoulder.github.com/odeint-v2/doc/index.html -------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? In Christ, Steven Watanabe

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[GIL] copy_and_convert_pixels vs transform_pixels
by Mateusz Loskot 27 Sep '12

27 Sep '12

Hi, What is relation, if any, and differences between these two Boost.GIL algorithms? They seem to be similar or the copy_and_convert_pixels seems like a specialisation of the transform_pixels. Is that correct understanding of these algorithms? Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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How to Boost serialize a Eigen::Matrix class
by Dip Ghosh 27 Sep '12

27 Sep '12

Hi, I have used Eigen::Matrix class in my project. Now i wants to serialize the value of it through Boost::Serialize. Can someone help me on how to achieve that. My class is following, class RandomNode { private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & is_leaf_; ar & depth_; ar & num_classes_; ar & num_features_; // Split node members ar & random_feature_indices_; ar & random_feature_weights_; ar & threshold_; ar & leftChild_; ar & rightChild_; } bool is_leaf_; int depth_; int num_classes_; int num_features_; // Split node members VectorXi random_feature_indices_; VectorXd random_feature_weights_; double threshold_; RandomNode* leftChild_; RandomNode* rightChild_; // Methods and so on } And i am getting the following error : /usr/include/boost/serialization/access.hpp:118:9: error: ‘class Eigen::Matrix<double, 10000, 1>’ has no member named ‘serialize’ thanks in advance. Regards, Dip

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Preprocessor sequence of "pairs"
by driscoll＠cs.wisc.edu 26 Sep '12

26 Sep '12

I have a question about the use of the preprocessor library. I'll describe my ultimate goal in a moment, but I've simplified my first problem to the following. Also, I know what I'm doing looks a lot at first glance like Fusion's ADAPT_STRUCT, but I took a quick look at that documentation and I don't think it matches. However, if you disagree with me and think it does, or can suggest a totally different solution, feel free to describe how. == My problem == I don't like C's struct syntax, so I'm trying to define my own. (</sarcasm> Really for purposes of this section I'm just doing this to figure out all the steps I'll need.) What I want to do is something like the following: #include <boost/preprocessor/seq/for_each.hpp> #define DEFINE_FIELD(r, os, field_pair) [....] #define DEFINE_STRUCT(struct_name, fields) \ struct struct_name { \ BOOST_PP_SEQ_FOR_EACH(DEFINE_FIELD, ~, fields) \ } DEFINE_STRUCT(mystruct, (int, x)(int, y)(double, z)) but this doesn't work, because the sequence is made up of pairs instead of single preprocessor arguments. (GCC complains about "macro "BOOST_PP_SEQ_SIZE_0" passed 2 arguments, but takes just 1" and same for PP_EXPR_IIF_0.) I can get it to work by double-parenthesizing the stuff in the sequence (saying "((int, x))((int, y))((double, z))") then defining DEFINE_FIELD as follows: #define DEFINE_FIELD_REAL(type, name) type name; #define DEFINE_FIELD(r, os, field_pair) DEFINE_FIELD_REAL field_pair but this is less than optimal. Is there a way that I can do this easily, or would I effectively have to re-implement SEQ_FOR_EACH? (And how hard would that be if it's necessary?) == What I'm actually trying to do == What I'm actually doing is trying to write a macro that will define a function like the following: DEFINE_SERIALIZED_STRUCT(mystruct, (int, x)(int, y)(double, z)) | V struct mystruct { int x; int y; double z; }; void serialize(ostream & os, mystruct const & s) { os << "x: " << s.x << "\n"; os << "y: " << s.y << "\n"; os << "z: " << s.z << "\n"; } (I didn't see a way to recover the field names from a Fusion-adapted struct -- from what I can tell, it more just seems to be a way to iterate over the fields.)

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autoconf/automake and boost
by ilya shlyakhter 26 Sep '12

26 Sep '12

Dear Boosters, Can you point me to instructions for specifying dependency on Boost in an autoconf/automake project? I'd like the configure script to have an option --with-boost=... to point to a Boost installation, to specify a minimum required Boost version, and to require the presence of particular Boost libraries. Searching the list and the web does not seem to give a definitive answer. Thanks for help, Ilya

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GGL: cartesian_to_spherical_equatorial2 conversion returning nan and not returning false (failed)
by David Doria 25 Sep '12

25 Sep '12

Using this: #include <boost/geometry/geometry.hpp> #include <iostream> int main() { namespace bg = boost::geometry; // bg = 'B'oost 'G'eometry namespace cs = bg::cs; // cs = 'C'oordinate 'S'ystem typedef bg::model::point<long double, 3, cs::cartesian> CartesianType; CartesianType cartesian(-6.89, -1.61, -1.64); // (theta, phi) typedef bg::model::point<long double, 2, cs::spherical<bg::degree> > SphericalType; SphericalType spherical; bg::strategy::transform::from_cartesian_3_to_spherical_equatorial_2<CartesianType, SphericalType> strategy; bg::transform(cartesian, spherical, strategy); std::cout << "cartesian: " << bg::dsv(cartesian) << std::endl << "spherical: " << bg::dsv(spherical) << std::endl; return 0; } I am getting the second coordinate of 'spherical' equal to 'nan'. I stepped through the Boost code, and got to this in strategy_transform.hpp: template <typename P, typename T> inline bool cartesian_to_spherical_equatorial2(T x, T y, T z, P& p) { assert_dimension<P, 2>(); set_from_radian<0>(p, atan2(y, x)); set_from_radian<1>(p, asin(z)); return true; } Here you see asin(z) . asin() requires the argument to be [-1,1] (http://www.cplusplus.com/reference/clibrary/cmath/asin/). However, this should just be the z component of any Cartesian point right? Is there some restriction on the input Cartesian point to cartesian_to_spherical_equatorial2 (and hence the from_cartesian_3_to_spherical_equatorial_2 strategy)? I see a restriction on from_cartesian_3_to_spherical_polar_2: \note If x,y,z point is not lying on unit sphere, transformation will return false but I don't see the same restriction on from_cartesian_3_to_spherical_equatorial_2. Additionally, it doesn't seem to just be a missing comment because the transform() call actually returns true even though this point is not on the unit sphere. If I normalize the point and call the function: CartesianType cartesian(-0.94862, -0.22167, -0.22580); The conversion seems to work successfully, and the call still returns true. Any thoughts? Is this a bug? If not, why is the function not returning false? And better, shouldn't this condition have at least an assertion (i.e. if the norm != 1, then return false or throw)? Thanks, David

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[Fusion] BOOST_FUSION_ADAPT_STRUCT with templated member
by Nevin Liber 25 Sep '12

25 Sep '12

The following piece of code: #include <boost/fusion/include/adapt_struct.hpp> template<int a, int b> struct AB {}; BOOST_FUSION_ADAPT_STRUCT( , Silly, (AB<2,3>, ab)) fails with: main.cpp:8:15: error: macro "BOOST_FUSION_ADAPT_STRUCT" passed 3 arguments, but takes just 2 main.cpp:6:1: error: 'BOOST_FUSION_ADAPT_STRUCT' does not name a type I am assuming this is because the preprocessor splits line 8 into 'AB<2', '3>', 'ab'. How do I work around this? Regards, -- Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (847) 691-1404

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b2 build problem: fatal error C1189: #error : "This is a GCC specific test case"
by Gunther Laure 25 Sep '12

25 Sep '12

Hi guys! I am getting a build error during build configuration using Visual Studio 2010: ...found 25 targets... ...updating 3 targets... compile-c-c++ C:\Users\glaure\SvnProject\SW_APP\3rdparty\test\boost\bin.v2\libs\regex\build\msvc-10.0\debug\address-model-64\threading-multi\has_icu_test.obj has_icu_test.cpp libs\regex\build\has_icu_test.cpp(12) : fatal error C1083: Cannot open include file: 'unicode/uversion.h': No such file or directory And more important: compile-c-c++ C:\Users\glaure\SvnProject\SW_APP\3rdparty\test\boost\bin.v2\libs\math\config\msvc-10.0\debug\address-model-64\threading-multi\has_gcc_visibility.obj has_gcc_visibility.cpp libs\math\config\has_gcc_visibility.cpp(7) : fatal error C1189: #error : "This is a GCC specific test case". The error is only reproduceable when i am using the --build-dir option of b2. Example: b2.exe -j8 install --build-dir=C:/boost_test --libdir=C:/boost_lib/release address-model=64 --prefix=C:/boost --without-python link=shared threading=multi variant=release Of course boost builds successfully, but the problem is that Visual Studio thinks that the build failed. These checks are not done if you build boost within the source tree. Currently I am using boost 1.50 Bye Gunther

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Boost.Serialization and ordering of multimap elements with the same key
by Jeremiah Willcock 25 Sep '12

25 Sep '12

At least in C++11, std::multimap is required to be stable for elements with the same key. However, serializing and then deserializing a multimap with Boost.Serialization can change the order of elements with the same key to be different than their order in the input multimap. Would it be possible to change multimap deserialization (since serialization appears to preserve the order already) to ensure that the output multimap exactly matches the input one? Thank you. -- Jeremiah Willcock

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boost::graph find the cycle
by tolik levchik 24 Sep '12

24 Sep '12

The following code http://ideone.com/MbvUI outputs 'false', why?

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