Re: Simple hash or pseudo-random function

[gautier_niouzes@hotmail.com]

Le lundi 16 juillet 2018 19:17:49 UTC+2, Jeffrey R. Carter a écrit :

> Not sure what you mean by "an integer in a range of minimum length 365". You 
> could simply use a RNG to generate 64-bit values and xor them with your values 
> if you want a 64-bit result. By setting the initial seed, the sequence would be 
> repeatable. Ada.Numerics.Discrete_Random would probably serve. If it's too slow, 
> the PragmAda Reusable Components includes KISS, a very fast, pretty good RNG. It 
> produces 32-bit values, so you'd probably need to call it twice.

The 64-bit value is the *input* and the output is a function of that input only.
e.g.
10562032 gives always 211
31375393 gives always 31
85232830 gives always 172
NB: the input codes can appear in a different order, so a pseudo-random *sequence* cannot be used.

I've tested different RNG's by initializing them with the input code and using only the first pseudo-random value using that seed. The good news is that they seem uniformly distributed even with successive seed values, but they are not random enough when seeds are similar. I'll check Marius' solution, or a hash function like CRC.