July 2012 - Boost - lists.boost.org

[test] Trunk broken: What happened to test_exec_monitor?
by John Maddock 21 Sep '12

21 Sep '12

Testing on Trunk is apparently broken as the test_exec_monitor target has been removed from Boost.Test Trunk as of revision #74642. A quick grep shows 22 Jamfiles and over 200 targets dependent upon this. Whats happened? John.

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[build] 1.49 unable to bootstrap boost
by yuri kilochek 12 Sep '12

12 Sep '12

Not sure if this goes here. On Windows 7, when I try to do bootstrap on a freshly unzipped boost 1.49 at the root directory, I get the following output: Building Boost.Build engine But that is as far as it gets before os terminates whatever it is doing with this (roughly translated from russian): **** STACK SIZE EXCEEDED **** **** WHILE PERFORMING RECURSION IN BATCH MODE **** Recursion depth=654, Stack usage=90 percent. **** BATCH PROCESSING ABORTED **** Is there a way to build boost bypassing this?

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[Variant] C++11 variadic template implementation
by Florian Goujeon 11 Sep '12

11 Sep '12

Hi Boosters, I'd like to know if anybody were working on a C++11 version (using variadic templates) of Boost.Variant. I currently use the 'classic' version in my project, but since I need more-than-20-type variants, the compilation take a lot of time (extending the number of types that variant can support forces you to disable the use of precompiled headers). Plus, I'll need to use 70 type variants (MPL lists are physically limited to 50 types). If nobody has started to implement such a version yet, I'd be pleased to contribute. I've written an implementation. It's incomplete and far from perfect, but it could (hopefully) be a viable working basis.

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[intrusive] patch to resolve compiler error for WinCE
by David Deakins 09 Sep '12

09 Sep '12

Hi Ion, I had a little bit of time to look into the compile error mentioned in ticket 6841 and determine a patch from detail/mpl.hpp that I think should resolve it. The patch is attached to that Trac ticket, although I could also just go ahead and apply it if you like. Thanks, -Dave

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[test] Boost.Test unreleased since November 2009 ?
by Mathieu Champlon 02 Sep '12

02 Sep '12

Hi, I've noticed that no merge has been made from trunk to the release branch for Boost.Test since November 2009, meaning that a lot of bug fixes and features have remained unreleased. Is it on purpose ? Thanks, MAT.

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Review Request: odeint
by Mario Mulansky 29 Aug '12

29 Aug '12

Hi, after getting some good amount of positive feedback on our talk at boostcon we are now asking for a formal review process of the odeint library, currently hosted on github: https://github.com/headmyshoulder/odeint-v2 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 The code is hosted on github: https://github.com/headmyshoulder/odeint-v2 Documentation/Tutorial: http://headmyshoulder.github.com/odeint-v2/doc/index.html We are, of course, looking for a review manager as well. Thanks! Karsten and Mario

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[multiprecision] Some rvalue reference experiments (performance inhancements #1)
by John Maddock 20 Aug '12

20 Aug '12

Folks, I've started to work through some of the points that came up in the multiprecision review, starting with further rvalue reference support. The idea (due to Marc Glisse) was to add operator overloads that look something like: Number&& operator+(Number&&a, const Number& b) { return static_cast<Number&&>(a += b); } Using my Polynomial Horner evaluation scheme as an example the number of temporaries dropped as follows: Type # temporaries No expression templates, no rvalue refs 24 No expression templates, rvalue refs 1 Expression template 0 Which is pretty impressive, but not necessarily typical usage, so by way of "real world" tests, I compared the times taken to evaluate Boost.Math's Bessel function test cases to 50 decimal places: Library Time/s # Allocations MPFR/mpreal (no ET's or rvalue refs) 9.4 13226029 MPFR/mpfr_class (ET's) 6.3 3948316 MPFR/mp_number(ET's) 6.0 2683646 GMP/mp_number(no ET's) 5.2 4186977 GMP/mp_number(ET's) 5.0 2594441 As you can see the number of allocations required when using mp_number with ET's turned off is almost double that without, I guess this is because many statements are similar to: a = b op c; Where a temporary is still required when relying on rvalue refs, but not for expression templates. Having said that the times are getting much closer now.... John.

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Is there any interest in getting pseudo random number generation using preprocessor at compile time into the Preprocessor library?
by Alexander Stoyan 20 Aug '12

20 Aug '12

The complete code, approach and efficiency proofs I described in my blog: http://alexander-stoyan.blogspot.com/2012/07/getting-pseudo-random-numbers-a t.html Need your opinion regarding the relevance and the approach correctness of the feature. Thank you in advance.

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[odeint] Iterator semantics
by Karsten Ahnert 19 Aug '12

19 Aug '12

Hi, we have posted a review request for odeint (a library for solving ordinary differential equations) on this list some days ago. An ODE is dx/dt = f(x(t)) and one is looking for the solution x(t) which is a function of t. Solving ODEs is usually an iterative task, so one starts with x(0) and iteratively applies a solver to obtain a discretized (and approximated) representation of the solution: x(0) -> x(dt) -> x(2*dt) -> x(3*dt) -> ... I played around with an iterator which is doing exactly this iterative procedure. For example, it can be used via odeint::runge_kutta4< state_type > stepper; // ode solver std::array< double , 3 > x = {{ 10.0 , 10.0 , 10.0 }}; // initial state double res = std::accumulate( // parameters : solver , ode , state , time , time_step make_const_step_iterator_begin(stepper, lorenz(), x, 0.0, 0.01) , make_const_step_iterator_end( stepper, lorenz(), x, 1.0, 0.01) , 0.0 , []( double sum, const state_type &x) { return sum + x[0]; } ); The first iterator increments the time until the time of the second iterator is rearched t=0.0 -> t=0.01 -> t=0.02 -> .. t=1.0 and the first component of the solution is accumulated. In principle, this approach works quite well, but there are some problems at least semantically. Maybe someone here has some comments or ideas on this: The defintion of this iterator is: template< class Stepper , class System , class StepperTag > class const_step_iterator : public boost::iterator_facade < const_step_iterator< Stepper , System , StepperTag > , typename Stepper::state_type const , boost::single_pass_traversal_tag > { ... }; It is a single pass iterator, so it can only check for equality of two iterators. This is problematic since equality here means that the time (t) of the begin iterator is smaller then the time of the end iterator. To ensure commutativity of the != or == operation I needed to flag the begin and end iterator explicitly. This is the reason for the two factory functions make_const_step_iterator_begin and make_const_step_iterator_end, which are doing this flagging. The second semantically problem is that the end iterator in principle does not need to know the stepper as well as the system (lorenz() in the above example). But all algorithms from the standard library and Boost.Range assume that the begin and end iterator are of same type. Therefore you have to put the stepper and the system into the end iterator too. Of course, there are techniques like type erasure which might solve this problem, but they introduce some run-time overhead which we want to avoid here. Any ideas or comments about this? P.S. The code can be found in the iterator branch in odeint: boost/numeric/odeint/iterator/const_step_iterator.hpp and some examples libs/numeric/odeint/examples/const_step_iterator.cpp git clone -b iterator git@github.com:headmyshoulder/odeint-v2.git

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[date_time] warning removal
by Vicente J. Botet Escriba 15 Aug '12

15 Aug '12

Hi, Attached a patch to remove most of the warnings below. Could I commit it? There are 4 warnings I want to check ../../../boost/date_time/period_formatter.hpp:117:47: warning: unused parameter 'separator' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:118:47: warning: unused parameter 'start_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:119:47: warning: unused parameter 'open_end_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:120:47: warning: unused parameter 'closed_end_delim' [-Wunused-parameter] where void delimiter_strings(const string_type& separator, const string_type& start_delim, const string_type& open_end_delim, const string_type& closed_end_delim) { m_period_separator; m_period_start_delimeter; m_open_range_end_delimeter; m_closed_range_end_delimeter; } and private: range_display_options m_range_option; string_type m_period_separator; string_type m_period_start_delimeter; string_type m_open_range_end_delimeter; string_type m_closed_range_end_delimeter; }; Is an assignment missing or it was a typo while trying to avoid the warning? Best, Vicente ../../../boost/date_time/date.hpp:194:55: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date.hpp:195:67: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_duration.hpp:128:57: warning: extra ';' inside a struct [-pedantic] ../../../boost/date_time/date_duration.hpp:138:69: warning: extra ';' inside a struct [-pedantic] ../../../boost/date_time/date_duration.hpp:35:73: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_generators.hpp:37:30: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_generators.hpp:38:39: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:43:32: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:56:45: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:57:48: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_names_put.hpp:233:8: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_names_put.hpp:45:26: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/dst_transition_generators.hpp:21:38: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/custom_time_zone.hpp:46:7: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/custom_time_zone.hpp:47:40: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/local_date_time.hpp:211:31: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/posix_time_zone.hpp:118:39: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/period_formatter.hpp:117:47: warning: unused parameter 'separator' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:118:47: warning: unused parameter 'start_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:119:47: warning: unused parameter 'open_end_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:120:47: warning: unused parameter 'closed_end_delim' [-Wunused-parameter] ../../../boost/date_time/time_duration.hpp:254:57: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:22:77: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:33:45: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:34:48: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:35:64: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:36:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:37:66: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:38:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:39:64: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:40:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_zone_base.hpp:42:24: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_zone_base.hpp:43:33: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/wrapping_int.hpp:37:42: warning: extra ';' inside a class [-pedantic]

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