Re: [boost] [random] new threefry random engine

On 02 May 2014, at 13:39, John Salmon wrote:

On Fri, May 2, 2014 at 1:26 AM, Steven Watanabe wrote:

...

AMDG

On 04/27/2014 05:39 AM, Mathias Gaunard wrote:

...

With a single, stateless generator, everything is much simpler. One seed, one generator, completely reproducible results regardless of scheduling. The interface i want to have is this:

#pragma omp for for(int i=0; i

The proposed RandomFunction doesn't quite work this way. It produces random numbers in blocks. (For instance, the threefry engine that started this thread, uses a 256-bit block size.)

Yes. But with C++11 initializer lists, random_value is a one-liner:

unsigned random_value(unsigned i){ return Threefry<2, unsigned>()({i})[0]; }

Without initializer lists, you would need another line for a declaration of a domain_type.

Alternatively, you may prefer to let a distribution do the rescaling for you:

Threefry<2,unsigned> prf; uniform_real_distribution<float> zero_one(0., 1.); #omp for(int i=0; i

John Salmon

The zero_one distribution can do any amount of call to the urng. E.g. the current normal_distribribution uses ziggurat with rejection sampling. The previous version uses Box Muller and consumed an even amount of random numbers. The only way I can see "counter_based_urng(prf, {i})” to be able to generate an arbitrary number of random values is when it has it’s own internal counter. In that case it’s best to use a random engine adaptor. counter_based_engine< Threefry<2,unsigned> > eng; uniform_real_distribution<float> zero_one(0., 1.); eng.seed(thread_id); for(int i=0; i