[Boost-bugs] [Boost C++ Libraries] #1856: minstd_rand returning different values in 1.35.0 than in 1.34.1

Subject: [Boost-bugs] [Boost C++ Libraries] #1856: minstd_rand returning different values in 1.35.0 than in 1.34.1
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-04-24 05:01:08


#1856: minstd_rand returning different values in 1.35.0 than in 1.34.1
---------------------------------------------------+------------------------
 Reporter: Greg Landrum <greg.landrum_at_[hidden]> | Owner: no-maintainer
     Type: Bugs | Status: new
Milestone: Boost 1.36.0 | Component: random
  Version: Boost 1.35.0 | Severity: Problem
 Keywords: |
---------------------------------------------------+------------------------
 After moving from boost 1.34.1 to 1.35.0 I have noticed that the
 sequence of values returned by the minstd_rand generator has changed.
 This sample code (included in the attachment) generates different values
 with 1.35.0 than
 it did with 1.34.x and 1.33.x:

 {{{
   typedef boost::minstd_rand rng_type;
   typedef boost::uniform_int<> distrib_type;
   typedef boost::variate_generator<rng_type &,distrib_type> source_type;
   rng_type generator(42u);

   unsigned int seeds[] = {12,23,42};

   distrib_type dist(0,INT_MAX);
   source_type randomSource(generator,dist);

   for(unsigned int i=0;i<3;++i){
     generator.seed(seeds[i]);
     std::cerr << seeds[i];
     for(unsigned int j=0;j<5;++j){
       unsigned int bit = randomSource();
       std::cerr<<" "<<bit%1024;
     }
     std::cerr<<std::endl;
   }
 }}}

 Output with v1.35.0:
 {{{
 12 691 854 1010 690 696
 23 444 337 394 1000 751
 42 404 8 37 977 972
 }}}
 and with v1.34.1:
 {{{
 12 691 844 854 975 292
 23 214 852 444 337 394
 42 883 404 943 348 8
 }}}
 If I use the mt19937 generator instead of minstd_rand, the sequences
 are the same across versions. In the event it matters, I'm using g++
 v4.1.3 on an Ubuntu Linux system.

--
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1856>
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