Actually I arrived at another fundamental question: 

I read '6.3 Random Number Generation' in the R Extensions Guide. It seems that 
it is not possible to set out of C++ the random seed (the wrapper RNGScope 
calls GetRNGstate() and PutRNGState() so it should have no extended 
functionality), which is very important when trying to produce reproducible 
results. So, I need a Mersenne-Twister, but I must be able to set the seed in 
every iteration. I think this brings me to the GSL library or - as long only 
normal random variates are needed - to the C++ std::random header?


Best Simon


On Feb 9, 2013, at 5:42 PM, Yan Zhou <zhou...@me.com> wrote:

>> 
>> This really is a BIG topic and worth a few more comments. Note that I wrote a
>> few related posts on RNGs at the Rcpp Gallery, see for example
>> 
>> http://gallery.rcpp.org/articles/timing-normal-rngs/
>> 
>> which compares the RNGs from R, C++11 and Boost. Simon just added Armadillo 
>> to
>> the list, we can add even more RNGs fromn other packages.
>  
> If it is of interest to anyone, I once timed Boost, C++11 and Random123 (A 
> high performance parallel RNG, 
> http://www.thesalmons.org/john/random123/releases/latest/docs/, It come with 
> a C++11 compatible RNG engine, can be used just like std::mt19937) once for 
> different compilers on Linux. I just uploaded them to 
> https://github.com/zhouyan/vSMC/wiki/RNG-performance-comparison
> 
> There are two benchmark, one for the performance of URNG (mt19937 etc). These 
> include those in C++11 <random> and Boost.Random, which are almost identical 
> in functionality (C++11 <random> is based on Boost.Random after all). Also 
> they include two URNG from Random123, threefry and philox (both come with 
> four basic configurations)
> 
> Another benchmark is the performance of generating distribution random 
> numbers (such as normal). The Random123 threefry2x64 was used for all 
> distribution and compilers, since it is the one with least performance 
> difference between compilers.
> 
> Compilers include,
> clang SVN with libstdc++ 4.7
> clang SVN with libc++ SVN
> gcc 4.7
> intel icpc 13
> 
> clang and gcc version also come with results when using AMD libm instead of 
> glibc. However, the benchmark are not Rcpp specific. They are compiled to 
> standalone C++ programs. But all these URNGs can be used Rcpp. As 
> demonstrated in Dirk's example. 
> 
> Best,
> 
> Yan Zhou
> 

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