SFC64(seed=None)
SFC64
is a 256-bit implementation of Chris Doty-Humphrey's Small Fast Chaotic PRNG (). SFC64
has a few different cycles that one might be on, depending on the seed; the expected period will be about $2^{255}$
(). SFC64
incorporates a 64-bit counter which means that the absolute minimum cycle length is $2^{64}$
and that distinct seeds will not run into each other for at least $2^{64}$
iterations.
SFC64
provides a capsule containing function pointers that produce doubles, and unsigned 32 and 64- bit integers. These are not directly consumable in Python and must be consumed by a Generator
or similar object that supports low-level access.
State and Seeding
The SFC64
state vector consists of 4 unsigned 64-bit values. The last is a 64-bit counter that increments by 1 each iteration.
The input seed is processed by SeedSequence
to generate the first 3 values, then the SFC64
algorithm is iterated a small number of times to mix.
Compatibility Guarantee
SFC64
makes a guarantee that a fixed seed will always produce the same random integer stream.
A seed to initialize the BitGenerator
. If None, then fresh, unpredictable entropy will be pulled from the OS. If an int
or array_like[ints]
is passed, then it will be passed to SeedSequence
to derive the initial BitGenerator
state. One may also pass in a SeedSequence
instance.
BitGenerator for Chris Doty-Humphrey's Small Fast Chaotic PRNG.
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