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Help with my first compilation with uBLAS
by Zdenek Hurak 20 Mar '03

20 Mar '03

Hello, Could anybody help me with my first compilation of a simple code using MATRIX class from uBLAS library? Namely, I can't set all the "include" properly. Have a look at the code snipet: ---------------------------------------------------------------------------------- #include <iostream.h> #include <stdlib.h> #include <boost/numeric/ublas/matrix.hpp> int main(int argc, char *argv[]) { using namespace boost::numeric::ublas; matrix<double> m (3, 3); for (int i = 0; i < m.size1 (); ++ i) for (int j = 0; j < m.size2 (); ++ j) m (i, j) = 3 * i + j; std::cout << m << std::endl; } ------------------------------------------------------------------------------------ I get an error message: main.cpp:21:42: boost/numeric/ublas/matrix.hpp: No such file or directory I use gcc/g++ on i386-linux and I set a parameter of the compiler to: --x-includes=/home/hurak/Documents/cpluspluswork/boost_1_29_0/ which is exactly the parent directory of "boost/numeric/ublas/matrix.hpp". Could you please explain to me what is still missing? I cannot find any example on the BOOST web. I am not much experienced in all this "include" stuff. Before delving deeper into the compiler options I would like to know if everything else is correct. Thanks Zdenek Hurak

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return type of bind object
by Faheem Mitha 20 Mar '03

20 Mar '03

Dear People, I have defined a function as follows. double accept_prob_fn(const double x, const double be, const double theta, const double a, const double b); Now, I define the temporary function object bind(accept_prob_fn, _1, be, theta, a, b); So this function object would return the first argument, x. However, I want to save this function object to a function object called foo, say. So I want to do something like Type foo = bind(accept_prob_fn, _1, be, theta, a, b); However, the problem I have is that I'm not sure what type foo should be. I forced an error with my compiler (to try to see what it thought the type of the rhs should be) by using Type as double, but all I got was brent.cc:9: cannot convert `boost::_bi::bind_t<double, double (*)(double, double, double, double, double), boost::_bi::list5<boost::arg<1>, boost::_bi::value<double>, boost::_bi::value<double>, boost::_bi::value<double>, boost::_bi::value<double> > >' to `double' in initialization Eww. I've tried looking at the documentation, but I find it pretty much incomprehensible. Could someone a) Tell me what "Type" should be. b) Give me some brief indication of the reasoning by which one might arrive at this conclusion, with appropriate references to the documentation? Thanks. Feel free to cc a copy of any reply to me. I'll check the mailing list via gmane in any case. Faheem.

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inner class functionlity with smart ptr.
by Saffi 19 Mar '03

19 Mar '03

Hi It is very common in Java when using pattern as EventListener having an inner class Adapter as the listener. I wanted that and more, I couldn't use "this" as the source of a shared ptr since then we will have to ref cnt to the same object ... Such scenario will cause a problem when one of the ref cnts will reach zero will delete the object and the other ref will point to a destructed object. The Problem : how define an inner class which would delegate functionality of the main class and break the ever annoying problem of giving ref to the main class. In Short two things are required : a. getSelf() functionality instead of "this" as a base for reference b. a glue to connect inner class to outer (in Java in terms of this example : ObjectWithAdapter.this) ---------------------------------------------------------------------------- -------------------------------------------------------------- Example : ObjectWithAdapter : the main class that need to register as listener IListener : listener interface ObjectWithAdapter::Adapter is the implementation of the IListener and delegates the message to the main class class IListener { virtual void helloListener(char *str)=0; }; class ObjectWithAdapter : public TMe<ObjectWithAdapter> { typedef RStrong<ObjectWithAdapter> RObjectWithAdapter; public: void helloListener(char *str) { // called from adapter } public: class Adapter : public TSon<ObjectWithAdapter>, IListener {public: void helloListener(char *str) { if (getPapa()) { getPapa()->helloListener(str); } } Adapter() { // register } virtual ~Adapter(void ) {// unregister } }; typedef RStrong<Adapter> RAdapter; RAdapter _adapter; ObjectWithAdapter() { } void initSons() { _adapter = RAdapter(new Adapter()); _adapter->initSon(getSelf()); } ~ObjectWithAdapter() { } }; typedef RStrong<ObjectWithAdapter> RObjectWithAdapter; ---------------------------------------------------------------------------- ---------------------------------------------------------------------------- ------------------------------------ Is such functionality is worthy piece of code for boost ? BTW my implementation works fine for me. -- Saffi

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boost smart pointers with memory managers
by shanypozin2003 19 Mar '03

19 Mar '03

Hi Is there a way to work with boost's smart pointers , for memory allocated by a memory manager ? I have a memory manager the pre allocates memory , and when i need new memory , i use the manager to supply it , and when i am finished, i return the memory to the memory manager . did i make my self clear ?. thanks shany

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AW: [Boost-Users] boost smart pointers with memory managers
by Jasper, Alexander 19 Mar '03

19 Mar '03

Hello Shany! > Is there a way to work with boost's smart pointers , > for memory allocated by a memory manager ? The smart pointer aren't actually responsible for allocation the memory. One option is overloading operator new and delete in the right way. If've done that and we use the smart pointers in conjuction with boost::pool. hope this helps. alex

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confusion on using date_time library
by jarry_cf＠hotmail.com 19 Mar '03

19 Mar '03

I am a newbie of boost and i want to use boost date_time library i have build the libboost_date_time.lib and boost_date_time.dll and put them in the lib path My devlope entironment is vc71 final beta+latest boost i get from cvs yesterday when i use some small code to test date_time_lib,i enconter with such error: error LNK2019: unresolved external symbol "public: char const * __thiscall boost::gregorian::greg_month::as_long_string(void)const " (? as_long_string@greg_month@gregorian@boost@@QBEPBDXZ) referenced in function "public: static class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl boost::date_time::month_formatter <class boost::gregorian::greg_month,class boost::date_time::simple_format>::format_month(class boost::gregorian::greg_month const &,class std::basic_ostream<char,struct std::char_traits<char> > &)" (?format_month @?$month_formatter@Vgreg_month@gregorian@boost@@Vsimple_format@date_time@ 3@@date_time@boost@@SAAAV?$basic_ostream@DU? $char_traits@D@std@@@std@@ABVgreg_month@gregorian@3@AAV45@@Z) code as follows: #ifndef DATE_TIME_INLINE #define DATE_TIME_INLINE #endif #include <boost/date_time/posix_time/posix_time.hpp> #include <iostream> using namespace boost::posix_time; int main(int , char*[] ) { std::cout << to_simple_string(second_clock::local_time()) << std::endl; } i use vc71 command line to compile anyone can tell me how to resolve such problems?thanks

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Problem with boost::timer on BCB
by sophtware 19 Mar '03

19 Mar '03

Hi All, Just an FYI for those interested. When compiling an application in RELEASE mode in BCB 5 the function std::clock() does not always return what you expect it to. In those cases, either an overflow or an invalid operation exception occurs. Using a "long double" for the return type prevents the exceptions, but the values are still incorrect (and way off!). If you don't need a resolution greater than one second, consider using the time(NULL) function instead. This one does work. -- Mike

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Using BOOST_CURRENT_FUNCTION
by Alisdair Meredith 19 Mar '03

19 Mar '03

We are updating our logging library at the moment, and as we now support multiple compilers I am looking to use BOOST_CURRENT_FUNCTION rather than many compiler checks through our code! Two questions: i/ Does it work with Borland C++Builder6? Although it seems to detect the correct macro, this is expanding to an empty string when used. ii/ Why is the logic implemented inside an empty function inside the ::boost::detail namespace? As everything is preprocessor based I do not see the benefit this brings, but assume it must have been done for a good reason so I am darned curious! <g> -- AlisdairM

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Poisson distribution for large mean
by kgolod0641 18 Mar '03

18 Mar '03

Hi, I am using poisson distribution (boost/random/poisson_distribution.hpp), and have encountered a problem when using a large mean. Let's say I'm setting up my poisson distribution with mean = MEAN, and repicking a sequence of 1000 random numbers. If I average out these 1000 numbers, I would expect to get MEAN (or very close to it). This works OK for mean < 745. Afterwards, no matter how large I set the mean, the same sequence of numbers is generated, with average of 745. Any help would be greatly appreciated!! Thank you, Ksenia

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RE: [Boost-Users] Re: help with mersenne_twister
by scleary＠jerviswebb.com 18 Mar '03

18 Mar '03

> -----Original Message----- > From: Jon Agiato [mailto:JonAgiato@nyc.rr.com] > > Thanks again for all the help! I was looking through > random-generators.html and see that there are in addition to > the Mersenne Twister, Linear Congruential, and Lagged > Fibonacci, five others: const_mod, additive_combined, > shuffle_output, rand48, and inversive_congruential. I am > assuming these are all good RNGs to use for comparison, am I wrong? const_mod: not an RNG; it is used as an implementation helper for other RNGs rand48: uses Linear Congruential algorithm additive_combined, shuffle_output: modifications to the Linear Congruential to try to make it better; so these two require Linear Congruential generator(s) as input > > And lastly (don't want to wear out my welcome.. lol), do > > you think there would be any benefit to using the advanced > > RNG classes in my research? > > Actually, I think it might be a good idea to do so for your > project. The > specializations provided by Boost.Random are well-known > RNGs that have been > published in research papers and used extensively. There > are undoubtedly > many other good specializations out there, but few are used > (mainly because > it is very hard to define what a "good RNG" is). > > Anyway, what I was thinking is that you might make some of your own > specializations that are known to be bad RNGs, and discuss > why they are bad. > Here is where my knowledge about RNGs end; I'm sure that > there are known bad > RNGs, but I don't know what they are. > > -Steve > > That's a great idea Steve, thanks! I am rather new to RNG > research but agree that a comparison of sorts would be good. > Could you or anyone here provide assistance, perhaps a short > example on how one would use one of the advanced RNGs Boost > provides? I use Boost a lot, and think that one of the > things it could really benefit from is more in depth > documentation, especially for those of us struggling to > utilize the library as quickly as possible. Then again, I > know that 1_30_0 should be out soon, so these developers have > enough to do on their plates. Look at the docs again; they explain what is necessary to specialize the generic algorithms. Note that you should be familiar with the generic RNG algorithms before attempting to specialize. For example, looking at the Linear Congruential RNG (which is the only RNG algorithm I'm familiar with), the algorithm is -- as specified in the Boost.Random docs: x(n+1) := (a * x(n) + c) mod m and boost::random::linear_congruential is declared as: template<class IntType, IntType a, IntType c, IntType m, IntType val> class linear_congruential; with a constructor of: explicit linear_congruential_fixed(IntType x0 = 1); Given this, the specialization boost::minstd_rand, declared as: typedef random::linear_congruential<long, 48271L, 0, 2147483647L, 399268537L> minstd_rand; uses the specific Linear Congruential algorithm: x(n+1) := (48271 * x(n)) mod 2147483647 again, x(0) is given by the constructor. (The last template argument is used for implementation validation, and does not affect the algorithm). You can experiment with adding your own specializations, or those defined by other people that are not found in Boost.Random. For example, here's one from "Numerical Recipes in C": typedef boost::random::linear_congruential<long, 69621L, 0, 2147483647L, 0> ParkMiller; As far as the Boost.Random docs go, I think that they are quite good (with the exception that the "val" template parameter is inconsistently documented). Most users of this library just need a random number generator, and the comparision chart with the general recommendation of mt19937 suits the bill for anyone who wants to quickly use the library. What you want to do is not just quickly use a single RNG; you have much more extensive needs, covering a larger range of RNG algorithms. Naturally, more time will be necessary to learn all the algorithms and the Boost implementations of them. -Steve

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