[Boost-bugs] [Boost C++ Libraries] #6353: memory layout specifiers doc clarification

Subject: [Boost-bugs] [Boost C++ Libraries] #6353: memory layout specifiers doc clarification
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-01-03 14:44:56

#6353: memory layout specifiers doc clarification
------------------------------+---------------------------------------------
 Reporter:  cppljevans        |       Owner:  garcia     
     Type:  Support Requests  |      Status:  new        
Milestone:  To Be Determined  |   Component:  multi_array
  Version:  Boost 1.48.0      |    Severity:  Cosmetic   
 Keywords:  stride docs       |  
------------------------------+---------------------------------------------
 http://www.boost.org/doc/libs/1_48_0/libs/multi_array/doc/reference.html#memory_layout


 Contains an ambiguous specification of storage ordering.  This lead me to
 making the wrong assumption about the meaning as shown by the following
 post:

 http://article.gmane.org/gmane.comp.lib.boost.user/72160


 As indicated in that post, *if* I had read the page:

 http://www.boost.org/doc/libs/1_48_0/libs/multi_array/doc/user.html#sec_storage


 the meaning or storage ordering would have been clear; however,
 I thought reading the reference.html#memory_layout page would have
 been the most unambiguous doc since it is the reference manual.

 I think the following snippet of code, or something similar, on
 the reference.html#memory_layout would make the meaning clearer:
 {{{
   std::vector<unsigned>
 strides_expected
   ( std::vector<unsigned> const& a_permut
       //storage order(a permutaion 0..a_lengths.size()-1)
   , std::vector<unsigned> const& a_lengths
       //length of axes.
   )
 {
     unsigned const n=a_lengths.size();
     std::vector<unsigned> strides(n);
     strides[permut_i[0]]=1;
     for( unsigned i=1; i<n; ++i)
     {
         unsigned i_prev=permut_i[i-1];
         strides[permut_i[i]]=strides[i_prev]*a_lengths[i_prev];
     }
     return strides;//strides of the axes
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6353>
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