Implementations of SFC32/SFC64 chaotic RNGs

[tertu-m]

This adds an implementation of the SFC32 and SFC64 chaotic RNGs.

There's some work left to be done regarding docs and formatting but they should work; I would like feedback on that.

EDIT: I'm also not even sure if this would be useful. One advantage it does have, perhaps, is that it does not require multiplication at all.

[dhardy]

At a glance, this seems like something we could add. But should we?

• I'd like some justification of why this is useful to people.
• Would you be willing to maintain this in case of future bug reports / requests?

[dhardy]

Unfinished?

[tertu-m]

I'll update that to mention the project now.

[tertu-m]

I would be willing to maintain this in the future.

My reasons for suggesting they are included that they are simple, fast generators (in my experience and based on what I could find on the internet they are slightly faster than Xoshiro and faster than PCG), they are high quality, they are reasonably well known as far as I am aware, and they are structurally different from the existing generators present in rand.

Additionally, in principle, stream support could be added as I mentioned in the comments, and this has been done by some people, but I don't think that functionality is very well studied. It is known that correlations exist early in two streams with different increments if the initial values provided for a, b, and c are the same.

EDIT: I guess you knew all that already; I read the comments later where that was mentioned. Anyway I guess it had been talked about in the past and the thought was maybe one more choice would be nice? This implementation doesn't have the counter panic issue, anyway.