On Wednesday, November 27, 2019 22:31 CET, François Pottier wrote:
Hello,
I am using zarith and would like to pick a random integer
comprised between 0 and some bound. I would like a function
Z.random of type Z.t -> Z.t, but this function seems to be
missing, and I am not sure how to program it in an efficient
and correct way. Any suggestions would be welcome. Thanks!
I tend to believe that the following idea might be good, but please check with real probability experts. I definitely am not one (but one of my best colleagues is one).
Let B be the bound.
You take a random number modulus 2*B. Let R be that number
You modelize the [0;B[ interval as a ring of numbers. For example if B is 5 : 0 -> 1 -> 2 -> 3 -> 4 -> 0 -> 1 -> .... ad infinitium
You memoize the previously given random number N
On that ring, you go R steps forward and obtain P. That is your new random number and on the next iteration the R would be that P
But check with an expert, I am not one
--
Basile