August 2006 - Boost-users - lists.boost.org

Re: [Boost-users] random number generator 160 bit.
by james.jones＠firstinvestors.com 10 Aug '06

10 Aug '06

From: "chun ping wang" <cablepuff(a)gmail.com> > [code skipped] > T n(Random::randint<T>(numeric_cast<T>(pow(2.0, num_digits - 1)), > numeric_cast<T>(pow(2.0, num_digits))) > [code skipped] > > now num_digits is number of bits. If i pass 160 bit as like for DSA > algorithm the program crashes. I pass 8 and it works, how come? Is there a > better way to do this? Oh f is any function that can deteremine if a number > is most likely a prime or not.... My guess is that numeric_cast<T>(pow(2.0, num_digits)) throws an overflow exception. I don't know what you're using for T, but obviously even a long long can't hold a 160-bit integer (at least not on any architecture I'm aware of). To verify this, catch on overflow_error and see if this prevents the crash. - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

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Boost.Random mt19937 seeding
by Matt Holland 10 Aug '06

10 Aug '06

Hi all, I'm having some difficulty understanding my options for seeding the base generators in mersenne_twister.hpp. I'm interested in the array initialization that is somewhat obtusely mentioned in the documentation. In boost/random/mersenne_twister.hpp I see the following relevant items: template<class It> mersenne_twister(It& first, It last) { seed(first,last); } ... template<class It> void seed(It& first, It last) { int j; for(j = 0; j < n && first != last; ++j, ++first) x[j] = *first; i = n; if(first == last && j < n) throw std::invalid_argument("mersenne_twister::seed"); } I gather that "It" is some kind of iterator, and the natural candidate would be something like std::vector<uint32_t>::iterator, but not having truly come to terms with templates, it is unclear to me how to actually call this. The following minimal code snippet fails to compile with g++ (gcc version 3.3 20030304 (Apple Computer, Inc. build 1671)). Errors below. #include <iostream> #include <vector> #include <boost/random.hpp> typedef boost::mt19937 Mt19937BaseGenerator; // base generator typedef boost::uniform_real<> UniformReal; // distribution // variate generator typedef boost::variate_generator<Mt19937BaseGenerator&, UniformReal> Mt19937UniformRealGenerator; int main() { std::vector<uint32_t> seedVector(4); seedVector[0] = 12345u; // make up some seeds seedVector[1] = 98765u; seedVector[2] = 12942u; seedVector[3] = 20343u; // attempt to seed with vector iterators Mt19937BaseGenerator mt19937Generator(seedVector.begin(), seedVector.end()); UniformReal distribution(0, 1); Mt19937UniformRealGenerator myGen(mt19937Generator, distribution); for (unsigned i = 0; i < 100; ++i) { std::cout << myGen() << std::endl; } return 0; } mt19937Seed.cpp: In function `int main()': mt19937Seed.cpp:18: error: no matching function for call to ` boost::random::mersenne_twister<uint32_t, 32, 624, 397, 31, 0x09908b0df, 11, 7, 0x09d2c5680, 15, 0x0efc60000, 18, 0x0c77666de>::mersenne_twister( __gnu_cxx::__normal_iterator<uint32_t*, std::vector<uint32_t, std::allocator<uint32_t> > >, __gnu_cxx::__normal_iterator<uint32_t*, std::vector<uint32_t, std::allocator<uint32_t> > >)' /sw/include/boost/random/mersenne_twister.hpp:43: error: candidates are: boost::random::mersenne_twister<uint32_t, 32, 624, 397, 31, 0x09908b0df, 11, 7, 0x09d2c5680, 15, 0x0efc60000, 18, 0x0c77666de>::mersenne_twister(const boost::random::mersenne_twister<uint32_t, 32, 624, 397, 31, 0x09908b0df, 11, 7, 0x09d2c5680, 15, 0x0efc60000, 18, 0x0c77666de>&) /sw/include/boost/random/mersenne_twister.hpp:69: error: boost::random::mersenne_twister<UIntType, w, n, m, r, a, u, s, b, t, c, l, val>::mersenne_twister(It&, It) [with It = __gnu_cxx::__normal_iterator<uint32_t*, std::vector<uint32_t, std::allocator<uint32_t> > >, UIntType = uint32_t, int w = 32, int n = 624, int m = 397, int r = 31, UIntType a = 0x09908b0df, int u = 11, int s = 7, UIntType b = 0x09d2c5680, int t = 15, UIntType c = 0x0efc60000, int l = 18, UIntType val = 0x0c77666de] /sw/include/boost/random/mersenne_twister.hpp:68: error: boost::random::mersenne_twister<UIntType, w, n, m, r, a, u, s, b, t, c, l, val>::mersenne_twister(UIntType) [with UIntType = uint32_t, int w = 32, int n = 624, int m = 397, int r = 31, UIntType a = 0x09908b0df, int u = 11, int s = 7, UIntType b = 0x09d2c5680, int t = 15, UIntType c = 0x0efc60000, int l = 18, UIntType val = 0x0c77666de] /sw/include/boost/random/mersenne_twister.hpp:60: error: boost::random::mersenne_twister<UIntType, w, n, m, r, a, u, s, b, t, c, l, val>::mersenne_twister() [with UIntType = uint32_t, int w = 32, int n = 624, int m = 397, int r = 31, UIntType a = 0x09908b0df, int u = 11, int s = 7, UIntType b = 0x09d2c5680, int t = 15, UIntType c = 0x0efc60000, int l = 18, UIntType val = 0x0c77666de] Any help? I always have a really hard time interpreting template-related compiler errors. Thanks, Matt -- Matt Holland Population Biology Graduate Group University of California Davis, CA 95616

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boost::serialization - serializing boost::smart_ptrs won't work
by Sascha Friedmann 09 Aug '06

09 Aug '06

Hello, I have a problem with serializing smart_ptrs. I have tried both the boost::scoped_ptr and the boost::shared_ptr but I get always the same error: Boost1-33\include\boost-1_33\boost\archive\detail\oserializer.hpp(566): error C2027: Use of undefined type "boost::STATIC_ASSERTION_FAILURE<x>" with [ x=false ] My example program: #include <boost/archive/tmpdir.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/shared_ptr.hpp> struct Foo { int i; Foo( int j ) : i( j ) { } template< class T > void serialize( T& ar, const unsigned int ver ) { ar & i; } }; struct Test { boost::shared_ptr< Foo > t1; boost::shared_ptr< Foo > t2; Test() : t1( new Foo( 3 ) ), t2( t1 ) { } template< class Ar > void save( Ar& ar, const unsigned int ver ) { ar << t1; ar << t2; } template< class Ar > void load( Ar& ar, const unsigned int ver ) { ar >> t1; ar >> t2; } BOOST_SERIALIZATION_SPLIT_MEMBER(); }; int main( int argc, char* argv[] ) { Test t; std::ofstream ofs( "test.txt" ); boost::archive::text_oarchive out( ofs ); out << t; } I hope someone can help me (google and the documentation couldn't :() Sascha Friedmann

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[lambda] Correct way to use lamda with boost.array?
by Michael Marcin 09 Aug '06

09 Aug '06

What is the proper syntax for using lamda with with array? i.e. how do I do something like namespace lambda = ::boost::lambda; boost::array< boost::array<int,2>, 4 > foo = {{ {-1,1}, {0,0}, {1,-1}, {2,-2} }}; std::for_each( foo.begin(), foo.end(), std::cout << lambda::constant( "first = " ) << lambda::_1[0] << ' ' << lambda::constant( "second = " ) << lambda::_1[1] << '\n' ); Thanks

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Using boost on msvc, having bjam link trouble with simple build
by Rod Morison 09 Aug '06

09 Aug '06

Mostly a bjam question: With bjam the link command is not finding the boost libs...I need help with the build setup: I built successfully and headers & libs are in C:\Boost... /Boost/include/boost-1_33_1/boost/... /Boost/lib/... I'm running Boost.Build from the boost-build-2.0-m11.tar.bz2 in c:\boost-build In building a small Boost.Threads app I get % bjam ...patience... ...found 258 targets... ...updating 2 targets... compile-c-c++ bin\msvc\debug\CreateThread.obj CreateThread.cpp msvc.link bin\msvc\debug\CreateThread.exe LINK : fatal error LNK1104: cannot open file 'libboost_thread-vc71-mt-gd-1_33_1.lib' ...updated 2 targets... My boost-build.jam is boost-build c:\\boost-build ; and my Jamroot is project : requirements <include>c:/Boost/include/boost-1_33_1 ; exe CreateThread : CreateThread.cpp ;

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[Signals] Newbie to understand boost-signal
by CG 09 Aug '06

09 Aug '06

Hi all, I am doing some research to use boost-signals library. I was reading the Tutorial of boost-signals library and have tested the Documents-View example , and understand the basic to use it. In the tutorial , there is a template function named visit_each , I suppose it is a iteration function to iterate all the slots or signals . However, there is not much information about how to use visit_each. I try to look into source code but as a newbie in template programming I really could not understand the source code. I wonder the creator of signal library have done some update on the tutorial and add in example on visit_each or other new interface/function Besides, apart from what mentioned in the tutorial, what are the benefit if a class is derived from trackable ? Sorry if my question are a bit weird.

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Building PDF format of Boost Documentation failed
by Ryo IGARASHI 09 Aug '06

09 Aug '06

Hi, I tried to build the PDF documentation of boost libraries. However, When I run bjam ordinary way, pdf build stopped with attached error. * HTML documentations are built correctly * CVS HEAD and RC_1_34_0 also failed What is the reason of this failure? /usr/local/src/boost/doc $ bjam --v2 pdf The following software version was used . OS: Debian GNU/Linux (sid/unstable) XSLTPROC: libxml 20626, libxslt 10117 and libexslt 813 (Using Debian official package "xsltproc" 1.1.17-2) DOXYGEN: 1.4.7 (Using Debian official package "doxygen" 1.4.7-1) JAVA: Sun Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_07-b03) (Using Debian official package "sun-java5-bin" 1.5.0-07-1) FOP: Apache FOP 0.20.5 (Using Debian official package "fop" 0.20.5-8) Boost: CVS HEAD/RC_1_34_0 My user_config.jam is also attached at the end. -- Ryo IGARASHI rigarash(a)gmail.com

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[boost][array] Multi-dimensional initialization
by Michael Marcin 09 Aug '06

09 Aug '06

At least under MSVC 8 I can do: boost::array< boost::array<int,2>, 4 > foo = { -1,1, 0,0, 1,-1, 2,-2 }; or int foo[4][2] = { {-1,1}, {0,0}, {1,-1}, {2,-2} }; or boost::array<int,2> foo[4] = { {-1,1}, {0,0}, {1,-1}, {2,-2} }; but not boost::array< boost::array<int,2>, 4 > foo = { {-1,1}, {0,0}, {1,-1}, {2,-2} }; just wondering why this is the case.

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format precision specifiers and strings
by Jason Nye 09 Aug '06

09 Aug '06

Hello all, I'm having trouble with boost format and precision specifiers with strings. The problem is that if I don't specify the 's' in the format string, a precision specifier does not truncate the string as I would expect: format("%.4s") % some_string The above will truncate some_string to the first four chars. format("%|.4s|") % some_string Same thing. However, the following does not truncate: format("%|.4|") % some_string This is confusing because the biggest boon to using boost::format for me is that the type specifier is (I thought) unnecessary. I would think that format would see the .4 and use that as precision if a floating point value was provided and use it as the length of the string if a string was provided. Is this a bug or is this the intended behavior? Thanks! Jason. If you have a procedure with ten parameters, you probably missed some. --Alan Perlis

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random number generator 160 bit.
by chun ping wang 09 Aug '06

09 Aug '06

Hi, I have a question how would i use boost to generate a 160 bit random integer. Heres the random number generator i wrote thanks to some of the boost community help. #ifndef RANDOM_NUMBER_HPP #define RANDOM_NUMBER_HPP #include <boost/random/shuffle_output.hpp> #include <boost/random/mersenne_twister.hpp> #include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> #include <Windows.h> #ifdef _linux_ #include <boost/nondet_random.hpp> #endif #include <boost/cast.hpp> // credit and thanks to Andrew Holden for help on this. namespace Random { typedef boost::kreutzer1986 base_generator_type; // typedef boost::mt19937 base_generator_type; typedef boost::uniform_int<> distribution_type; typedef boost::variate_generator<base_generator_type&, distribution_type> gen_type; // boost::random_device nondet_generator; //Declare the generator as a global variable for easy reuse #ifdef __linux__ boost::random_device dev; base_generator_type generator(dev()); #else base_generator_type generator(GetTickCount()); #endif /*************************************************** * initializes the random number generator * **************************************************/ void initialize() { for (int i = 0; i < 900; ++i) { #ifdef __linux__ generator.seed(dev()); #else generator.seed(GetTickCount()); #endif } } /*************************************************** * generates a random number between a and b * * @param a the starting range * * @param b the integer ending range * * @return N such that a <= N <= b * **************************************************/ template <class T> T randint (const T& a, const T& b) { //Check the parameters BOOST_STATIC_ASSERT(boost::is_integral<T>::value); assert (b >= a); //Set up the desired distribution gen_type ran_gen(generator, distribution_type(a, b)); //Get a random number return ran_gen(); } } #endif /* RANDOM_NUMBER_HPP */ Heres a code to generate random prime number. /*************************************************** * n <- random number with num_digits digits * * if n is even then n = n + 1; * * while is_prime(n, 150) * * { * * n = n + 2; * * } * * return n; * ***************************************************/ template <typename T> T boost::random_prime(boost::function<bool(const T&, const T&)> f, const unsigned int& num_digits) { BOOST_STATIC_ASSERT(is_integral<T>::value); T n(Random::randint<T>(numeric_cast<T>(pow(2.0, num_digits - 1)), numeric_cast<T>(pow(2.0, num_digits))) ); if (n%2 == 0) { ++n; } while (f(n, 20)) { n += 2; } return n; } now num_digits is number of bits. If i pass 160 bit as like for DSA algorithm the program crashes. I pass 8 and it works, how come? Is there a better way to do this? Oh f is any function that can deteremine if a number is most likely a prime or not.... Thanks.

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