[Boost-bugs] [Boost C++ Libraries] #5767: A bug in seeding with sequence in Mersenne Twister

Subject: [Boost-bugs] [Boost C++ Libraries] #5767: A bug in seeding with sequence in Mersenne Twister
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-08-09 23:58:37

#5767: A bug in seeding with sequence in Mersenne Twister
-------------------------------------------------+--------------------------
 Reporter:  Synge Todo <wistaria@…>              |       Owner:  no-maintainer
     Type:  Bugs                                 |      Status:  new          
Milestone:  To Be Determined                     |   Component:  random       
  Version:  Boost 1.47.0                         |    Severity:  Regression   
 Keywords:                                       |  
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 There is a bug in boost/random/mersenne_twister.hpp:
 {{{
    176          // fix up the state if it's all zeroes.
    177          if((x[0] & (~static_cast<UIntType>(0) << r)) == 0) {
    178              for(std::size_t j = 1; i < n; ++j) {
    179                  if(x[j] != 0) return;
    180              }
 }}}
 Since there is a typo in line 178 ("i < n" should be "j < n"), x[0] will
 always be reset to some constant (static_cast<UIntType>(1) << (w-1)).

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/5767>
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