Re: [Rd] Extreme bunching of random values from runif with Mersenne-Twister seed

2017-11-05 Thread Paul Gilbert
I'll point out that there is there is a large literature on generating pseudo random numbers for parallel processes, and it is not as easy as one (at least me) would intuitively think. By a contra-positive like thinking one might guess that it will not be easy to pick seeds in a way that will p

Re: [Rd] Extreme bunching of random values from runif with Mersenne-Twister seed

2017-11-05 Thread peter dalgaard
> On 5 Nov 2017, at 15:17 , Duncan Murdoch wrote: > > On 04/11/2017 10:20 PM, Daniel Nordlund wrote: >> Tirthankar, >> "random number generators" do not produce random numbers. Any given >> generator produces a fixed sequence of numbers that appear to meet >> various tests of randomness. By pi

Re: [Rd] Extreme bunching of random values from runif with Mersenne-Twister seed

2017-11-05 Thread Tirthankar Chakravarty
Duncan, Daniel, Thanks and indeed we intend to take the advice that Radford and Lukas have provided in this thread. I do want to re-iterate that the generating system itself cannot have any conception of the use of form IDs as seeds for a PRNG *and* the system itself only generates a sequence of

Re: [Rd] Extreme bunching of random values from runif with Mersenne-Twister seed

2017-11-05 Thread Duncan Murdoch
On 04/11/2017 10:20 PM, Daniel Nordlund wrote: Tirthankar, "random number generators" do not produce random numbers. Any given generator produces a fixed sequence of numbers that appear to meet various tests of randomness. By picking a seed you enter that sequence in a particular place and sub

Re: [Rd] Extreme bunching of random values from runif with Mersenne-Twister seed

2017-11-05 Thread Daniel Nordlund
Tirthankar, "random number generators" do not produce random numbers. Any given generator produces a fixed sequence of numbers that appear to meet various tests of randomness. By picking a seed you enter that sequence in a particular place and subsequent numbers in the sequence appear to be