[Rcpp-devel] mixing R's and C++'s RNGs and distributions

[Ramon Diaz-Uriarte]

On Wed, 24-06-2015, at 15:22, Matt D. <matdzb at gmail.com> wrote:
> On 6/24/2015 15:07, Ramon Diaz-Uriarte wrote:
>> Hi Matt,
>>
>> Thanks a lot for the details and the work. That is great! There is a
>> problem, though: in my particular case, I am uploading my package to
>> BioConcutor, and there the compiler for Win is 4.6.3 so I am restricted to
>> that. Including randutils will lead to an error during building the package
>> in Windows.
> Yeah, in this case I think replacing the source of entropy with 
> something else may be the compromise choice (it's a range eventually 
> passed to `mix_entropy`, so I'd investigate the effects on that).
> That all being in the meantime / while waiting for the toolchain to 
> catch up, of course...

But I wonder if it is worth the effort. 


>
> Best,
>
> Matt
>>
>> Best,
>>
>> R.
>>
>> On Wed, 24-06-2015, at 14:55, Matt D. <matdzb at gmail.com> wrote:
>>> On 6/22/2015 12:31, Ramon Diaz-Uriarte wrote:
>>>> Actually, I just noticed that things will not work if you need your package
>>>> to run on Windoze: Rtools uses gcc 4.6.3 there, and this will not work with
>>>> gcc 4.6 (neither in Linux nor Windows) with flag -std=c++0x or
>>>> -std=gnu++0x. I guess this should be fixable, but I do not know enough to
>>>> do it.
>>> Hi again!
>>>
>>> I've just tried with the work-in-progress, _experimental_ version
>>> available at the following location:
>>> https://rawgit.com/kevinushey/RToolsToolchainUpdate/master/mingwnotes.html
>>>
>>> // In particular, I've used "Windows native compiler for 64 bit Windows
>>> output mingw32mingw64_gcc-4.9.2.toolchain.tar.gz".
>>>
>>> This works better -- the only missing part is <thread> support :-(
>>> However, it is not exactly essential here, in that it's used solely in
>>> one place -- to get some extra entropy; that's all.
>>> After temporarily removing dependence on `std::this_thread::get_id()`,
>>> the example -- available at
>>> http://www.pcg-random.org/posts/ease-of-use-without-loss-of-power.html
>>> -- compiles and runs successfully.
>>>
>>> Incidentally,  one can get threads support for MinGW using MSYS2, which
>>> gives:
>>> Thread model: posix
>>> gcc version 4.9.2 (Rev5, Built by MSYS2 project)
>>>
>>> However, the MinGW that comes with Rtools uses the following:
>>> Thread model: win32
>>> gcc version 4.9.2 (GCC)
>>>
>>> I presume there must be a reason for that. There are certainly
>>> trade-offs present:
>>> https://wiki.qt.io/MinGW-64-bit#GCC_Threading_model_.28posix_vs_win32.29
>>> What hits us here is the "no C++11 <thread>, <mutex>, or <future> "
>>> ("C11" appears to be a typo) part for the win32 choice.
>>> // See also:
>>> https://stackoverflow.com/questions/17242516/mingw-w64-threads-posix-vs-win32
>>>
>>> Note that there's nothing multithreading-specific about the library, so
>>> even though I've also tested it with
>>> https://github.com/meganz/mingw-std-threads (warning: just something
>>> I've ran across while searching for multithreading support for MinGW
>>> built w/ win32 threading model, quality and license unknown) and also
>>> made it compile & work after a small patch (adding the std::hash
>>> specialization), it's probably possible to use another source of entropy
>>> here.
>>>
>>> I presume another idea would be to use a different GCC version, but
>>> that's rather tedious --
>>> https://stackoverflow.com/questions/25455829/using-a-different-gcc-version-from-that-included-with-rtools-with-rcpp-on-window
>>> Other than the above, I'm wondering myself what's the "official"
>>> recommendation for the C++11 threading support w/ Rcpp on Windows.
>>>
>>> Best,
>>>
>>> Matt

-- 
Ramon Diaz-Uriarte
Department of Biochemistry, Lab B-25
Facultad de Medicina
Universidad Autónoma de Madrid 
Arzobispo Morcillo, 4
28029 Madrid
Spain

Phone: +34-91-497-2412

Email: rdiaz02 at gmail.com
       ramon.diaz at iib.uam.es

http://ligarto.org/rdiaz