numpy.random.
SFC64
BitGenerator for Chris Doty-Humphrey’s Small Fast Chaotic PRNG.
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
int
array_like[ints]
SeedSequence
Notes
SFC64 is a 256-bit implementation of Chris Doty-Humphrey’s Small Fast Chaotic PRNG ([1]). SFC64 has a few different cycles that one might be on, depending on the seed; the expected period will be about
System Message: WARNING/2 (2^{255})
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System Message: WARNING/2 (2^{64})
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.
Generator
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.
References
“PractRand”
“Random Invertible Mapping Statistics”
state
Get or set the PRNG state
cffi
CFFI interface
ctypes
ctypes interface