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RE: [boost] Question about Boost.Random
by Kris Thielemans 09 Jul '04

09 Jul '04

Hi Anders you probably should read my email on this of a few days ago. The simple answer is to use typedef boost::variate_generator<engine_t&, distribution_t> rng_t; (i.e. with ref) It all makes sense, it's just hard to get from the doc in my opinion. Kris > // The following program illustrates a problem in Boost.Random. > > // Is this the desired behavior? > > // If so, what is the reason for this? > > // I use Boost version 1.31 and GCC version 3.3.3 on Suse 9.1 > > #include <vector> > #include <algorithm> > #include <boost/random.hpp> > > // Definition of the random number generator > typedef boost::mt19937 engine_t; > typedef boost::uniform_int<int> distribution_t; > typedef boost::variate_generator<engine_t, distribution_t> rng_t; > > int main() > { > const unsigned int N = 13, A = 0, B = 1000; > std::vector<int> run1(N), run2(N), run3(N); > > // Generate some random integers > { > engine_t engine; > distribution_t distribution(A,B); > rng_t rng(engine, distribution); > std::generate(run1.begin(), run1.end(), rng); > } > > // Verify that I get the same sequence if I start again > { > engine_t engine; > distribution_t distribution(A,B); > rng_t rng(engine, distribution); > std::generate(run2.begin(), run2.end(), rng); > } > > // It appears that the generator restarts for each generate, since > // the generate algorithm creates a copy of the functor so that > // its state is lost > { > engine_t engine; > distribution_t distribution(A,B); > rng_t rng(engine, distribution); > std::generate(run3.begin(), run3.begin()+N/2, rng); > std::generate(run3.begin()+N/2, run3.end(), rng); > } > > // For me it would seem more natural if the engine class would be a > // singleton, so that there can be only one object of any particular > // random generator engine type. > > // Our purpose for using random numbers is to simulate physical processes. > // I can't think of a case when there would be a need for several random > // engines, even if there can of course be many different random > // distributions in an application. > > // Having the same random number sequence in different parts of a > simulation > // can probably create very strange behaviour, since the numbers from the > // different engines of the same type will be perfectly correlated. > > // Perhaps other applications have use of several random engines? > > for(unsigned i=0; i<N; ++i) { > if(i==N/2) > std::cout<<"Halfway there!"<<std::endl; > std::cout > <<run1[i] > <<" == "<<run2[i] > <<" == "<<run3[i] > <<std::endl; > } > > return 0; > } > > // Anders Edin > // Sidec Technologies AB > >

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Re: [ublas-dev] Re: Boost Mathematicians
by Jeremy Graham Siek 09 Jul '04

09 Jul '04

Hi Paul, Yes, you've got the idea. The following document shows one such attempt to construct a system of traits for algebraic concepts: http://www.cs.rpi.edu/~schupp/entries/SOFTWARE/simpl/doc/AlgCpp.pdf also, more information is available starting at: http://www.cs.rpi.edu/~schupp/entries/SOFTWARE/simpl/ Cheers, Jeremy On Jul 7, 2004, at 7:32 PM, Paul C. Leopardi wrote: > Jeremy, Dave, > I think I get it. See below. > Best regards > On Thursday 08 July 2004 02:25, David Abrahams wrote: > > Jeremy Graham Siek <jsiek(a)osl.iu.edu> writes: > > > group_traits<T>::is_commutative > > is_commutative_group<T>::type > > is_commutative_group<T>::type::value > > OK, for a type where you have one operation (a group). > For a two operation type, I suppose you would then want > > is_ring<T>::type > is_ring<T>::type::value > > is_commutative_ring<T>::type > is_commutative_ring<T>::type::value > > Along these lines, you could build a header file called > arithmetic_traits.hpp > or something similar. The object of this file would be to describe > some of > the semantics of operator+, operator* and possibly other operators > when used > with various types. Eg. you could have say > > is_algebra< framed_multi<T,L,H>, T>::type > is_algebra< framed_multi<T,L,H>, T>::scalar_type > > This header would also be used to define the zero element of addition > and the > identity element of multiplication, if it exists. > > Once this header is established, you could build template libraries > which > perform arithmetic according to the axioms embodied in the traits. > Such a > library would not eg. assume that multiplication is commutative, it > would > check this at compile time. > > Note that there would also need to be a distinction between > approximate and > exact arithmetic. This especially affects associativity, where eg. > addition > of real numbers behaves differently from addition of floating point > numbers > due to loss of precision. eg. > http://h18009.www1.hp.com/fortran/docs/vf-html/pg/pg1round.htm > http://www.ibiblio.org/pub/languages/fortran/ch4-6.html > > > > > Yahoo! Groups Sponsor > > ADVERTISEMENT > <lrec_companion_043004.gif> > <l.gif> > > Yahoo! Groups Links > > • To visit your group on the web, go to: > http://groups.yahoo.com/group/ublas-dev/ > > • To unsubscribe from this group, send an email to: > ublas-dev-unsubscribe(a)yahoogroups.com > > • Your use of Yahoo! Groups is subject to the Yahoo! Terms of > Service. > > _______________________________________________ Jeremy Siek <jsiek(a)osl.iu.edu> http://www.osl.iu.edu/~jsiek Ph.D. Candidate, Indiana University Bloomington C++ Booster (http://www.boost.org) _______________________________________________

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boost::posix_time::ptime constructor from special values? ( eg, not_a_date_time )
by Richard Reitmeyer 09 Jul '04

09 Jul '04

Hello. Thanks for all your work in the boost::date_time code. It's very useful. I've got a question about constructing a ptime from special values. The documentation says it works, but I can't find the appropriate constructor in ptime.hpp. (I'm using 1.31.0.) Is this a bug, or am I missing something? Richard

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Partially specializing less<> with nested template class
by David B. Held 09 Jul '04

09 Jul '04

This is what I would like to do: template <class P1, class P2> struct sp { template <typename T> struct nested { }; }; template <typename T> struct less; template <class P1, class P2, typename T> struct less<sp<P1, P2>::nested<T> > : binary_function<...> { bool operator()(...); }; However, it doesn't work. From my research, it seems that the problem is that T is in a non-deduced context, but I don't see why that would be an issue, since this is how I expect it to get instantiated: less<sp<p1, p2>::nested<int> > comp; Thus, I don't see any deduction as being necessary, but obviously I don't exactly understand how to get what I want. Dave

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[regression] XSLT reports...
by Rene Rivera 09 Jul '04

09 Jul '04

For the regression reports that are generated with XSLT there is a rather annoying setting the master.css style sheet used for them. For some of the styles, legend, comment, and header-table, a fixed width attribute is used. If the width was small it would not be a problem. But the width is set to 800px. Which means that most people will end up scrolling left and right to see the complete content. If someone would nice enough to change these to a relative value, like 80%, it would be much appreciated. I'd do it myself, but I don't know if me changing the master.css in CVS has any effect on the test machines. -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com - 102708583/icq

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[ref] small problem with docs
by Jonathan Turkanis 09 Jul '04

09 Jul '04

The synopsis for unwrap_reference, at http://www.boost.org/doc/html/class.boost.unwrap_reference.html, is as follows: template<typename T> class unwrap_reference { public: // types typedef unspecified T; }; The second to last line should be 'typedef unspecified type;' Jonathan

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RE: [boost] Re: VC7.1 Building...
by Brian Carlson 09 Jul '04

09 Jul '04

>>If you want to build for vc7.1 you should use vc7.1. > > I did (bjam -sTOOLS=vc7.1 stage) and I get the following error: > > Vc7.1-tools.jam No such file or directory. ^ It's case sensitive. I did a search of the boost directory, and only a vc7-tools.jam, no vc7.1-tools.jam. I think that there is no jam file for vc7.1 in boost 1.29

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RE: [boost] min, max, GCC 2.95.3, and STLport
by Rozental, Gennadiy 09 Jul '04

09 Jul '04

Why subject configuration still failing on min/max according to Linux regression? Gennadiy.

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Patch for Boost.Threads
by Synge Todo 09 Jul '04

09 Jul '04

Dear Boosters, I found that the recent changes made on libs/thread/src/exceptions.cpp break the SGI MIPSpro compiler. Could somebody apply the following patch? Thank you in advance. Best regards, Synge Todo diff -crN boost.orig/libs/thread/src/exceptions.cpp boost/libs/thread/src/exceptions.cpp *** boost.orig/libs/thread/src/exceptions.cpp Wed Jul 7 02:20:55 2004 --- boost/libs/thread/src/exceptions.cpp Thu Jul 8 20:15:19 2004 *************** *** 12,17 **** --- 12,18 ---- #include <boost/thread/detail/config.hpp> #include <boost/thread/exceptions.hpp> + #include <cstring> #include <string> # ifdef BOOST_NO_STDC_NAMESPACE

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RE: [boost] min, max, GCC 2.95.3, and STLport
by Rozental, Gennadiy 08 Jul '04

08 Jul '04

> Are there any other failures regarding min/max you've noticed, or is it just the three tests I've mentioned? As far as I see everything still failing: See here http://tinyurl.com/yq9rw Gennadiy.

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