Permuted congruential generator (64bit, PCG64 DXSM)#
 class numpy.random.PCG64DXSM(seed=None)#
BitGenerator for the PCG64 DXSM pseudorandom number generator.
 Parameters:
 seed{None, int, array_like[ints], SeedSequence}, optional
A seed to initialize the
BitGenerator
. If None, then fresh, unpredictable entropy will be pulled from the OS. If anint
orarray_like[ints]
is passed, then it will be passed toSeedSequence
to derive the initialBitGenerator
state. One may also pass in aSeedSequence
instance.
Notes
PCG64 DXSM is a 128bit implementation of O’Neill’s permutation congruential generator ([1], [2]). PCG64 DXSM has a period of \(2^{128}\) and supports advancing an arbitrary number of steps as well as \(2^{127}\) streams. The specific member of the PCG family that we use is PCG CM DXSM 128/64. It differs from
PCG64
in that it uses the stronger DXSM output function, a 64bit “cheap multiplier” in the LCG, and outputs from the state before advancing it rather than advancethenoutput.PCG64DXSM
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 aGenerator
or similar object that supports lowlevel access.Supports the method
advance
to advance the RNG an arbitrary number of steps. The state of the PCG64 DXSM RNG is represented by 2 128bit unsigned integers.State and Seeding
The
PCG64DXSM
state vector consists of 2 unsigned 128bit values, which are represented externally as Python ints. One is the state of the PRNG, which is advanced by a linear congruential generator (LCG). The second is a fixed odd increment used in the LCG.The input seed is processed by
SeedSequence
to generate both values. The increment is not independently settable.Parallel Features
The preferred way to use a BitGenerator in parallel applications is to use the
SeedSequence.spawn
method to obtain entropy values, and to use these to generate new BitGenerators:>>> from numpy.random import Generator, PCG64DXSM, SeedSequence >>> sg = SeedSequence(1234) >>> rg = [Generator(PCG64DXSM(s)) for s in sg.spawn(10)]
Compatibility Guarantee
PCG64DXSM
makes a guarantee that a fixed seed will always produce the same random integer stream.References
State#
Get or set the PRNG state 
Parallel generation#

Advance the underlying RNG asif delta draws have occurred. 

Returns a new bit generator with the state jumped. 
Extending#
CFFI interface 

ctypes interface 