On 05/11/2017 10:58 AM, peter dalgaard wrote:
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
var
Le 05/11/2017 à 15:17, Duncan Murdoch a écrit :
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
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
> 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
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
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
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
In the code below, you seem to be essentially using the random number
generator to implement a hash function. This isn't a good idea.
My impression is that pseudo-random number generation methods are
generally evaluated by whether the sequence produced from any seed
"appears" to be random. Infor
Bill,
Appreciate the point that both you and Serguei are making, but the sequence
in question is not a selected or filtered set. These are values as observed
in a sequence from a mechanism described below. The probabilities required
to generate this exact sequence in the wild seem staggering to m
Another other generator is subject to the same problem with the same
probabilitiy.
> Filter(function(s){set.seed(s,
kind="Knuth-TAOCP-2002");runif(1,17,26)>25.99}, 1:1)
[1] 280 415 826 1372 2224 2544 3270 3594 3809 4116 4236 5018 5692 7043
7212 7364 7747 9256 9491 9568 9886
Bill Dunlap
Bill,
I have clarified this on SO, and I will copy that clarification in here:
"Sure, we tested them on other 8-digit numbers as well & we could not
replicate. However, these are honest-to-goodness numbers generated by a
non-adversarial system that has no conception of these numbers being used
fo
The random numbers in a stream initialized with one seed should have about
the desired distribution. You don't win by changing the seed all the
time. Your seeds caused the first numbers of a bunch of streams to be
about the same, but the second and subsequent entries in each stream do
look unifor
Le 03/11/2017 à 14:24, Tirthankar Chakravarty a écrit :
Martin,
Thanks for the helpful reply. Alas I had forgotten that (implied)
unfavorable comparisons of *nix systems with Windows systems would likely
draw irate (but always substantive) responses on the R-devel list -- poor
phrasing on my par
Martin,
Thanks for the helpful reply. Alas I had forgotten that (implied)
unfavorable comparisons of *nix systems with Windows systems would likely
draw irate (but always substantive) responses on the R-devel list -- poor
phrasing on my part. :)
Regardless, let me try to address some of the conce
If I interpret the original message as “I think there’s something wrong with
R's random number generator”:
Your assumption is that going from the seed to the first random number is a
good hash function, which it isn’t.
E.g., with Mersenne Twister it’s a couple of multiplications, bit shifts, xors
> Tirthankar Chakravarty
> on Fri, 3 Nov 2017 13:19:12 +0530 writes:
> This is cross-posted from SO
> (https://stackoverflow.com/q/47079702/1414455), but I now
> feel that this needs someone from R-Devel to help
> understand why this is happening.
Why R-devel -- R-hel
This is cross-posted from SO (https://stackoverflow.com/q/47079702/1414455),
but I now feel that this needs someone from R-Devel to help understand why
this is happening.
We are facing a weird situation in our code when using R's [`runif`][1] and
setting seed with `set.seed` with the `kind = NULL`
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