Permuted Congruential Generator 2.0 (64bit Multiplier, DXSM Output)¶

class randomgen.pcg64.PCG64DXSM(seed=
None
, inc=None
)¶ Container for the PCG64 updated with a 64bit mult using DXSM output func.
Preconfigured alias for PCG64 with variant=”dxsm” and mode=”sequence”. This bit generator will likely become the default in NumPy in the near future ([3]).
 Parameters:¶
 seed=
None
¶ Random seed initializing the pseudorandom number generator. Can be an integer in [0, 2**128), a SeedSequence instance or None (the default). If seed is None, then
PCG64DXSM
will used a SeedSequence initialized with system entropy to Seed the generator inc=
None
¶ The increment in the LCG. Can be an integer in [0, 2**128) or None. If inc is None, then it is initialized using the same SeedSeuqnce used for seed.
 seed=
 lock¶
Lock instance that is shared so that the same bit git generator can be used in multiple Generators without corrupting the state. Code that generates values from a bit generator should hold the bit generator’s lock.
 Type:¶
 seed_seq¶
The SeedSequence instance used to initialize the generator if mode is “sequence” or is seed is a SeedSequence. None if mode is “legacy”.
 Type:¶
{None, SeedSequence}
Notes
Random variates are generated by permuting the output of a 128bit LCG
\[s_{n+1} = m s_{n} + i \mod 2^{128}\]where \(s\) is the state of the generator, \(m\) is the multipler and \(i\) is the increment. The multipler is a 64bit unsigned integer with good spectral properties. The output of the LCG is the permuted using the DXSM output function which is similar to an Xorshift ([1], [2]).
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 RNG is represented by a 128bit unsigned integer.
State and Seeding
The
PCG64DXSM
state vector consists of 2 unsigned 128bit values, which are represented externally as Python ints.PCG64DXSM
is seeded using a single 128bit unsigned integer. In addition, a second 128bit unsigned integer is used as the increment in the LCG.Compatibility Guarantee
PCG64DXSM
makes a guarantee that a fixed seed and will always produce the same random integer stream.Examples
Parallel Features
PCG64DXSM
can be used in parallel applications by callingadvance
with a different value on each instance to produce nonoverlapping sequences.>>> from numpy.random import Generator >>> from randomgen import PCG64DXSM >>> rg = [Generator(PCG64DXSM(1234, i + 1)) for i in range(10)] >>> for i in range(10): ... rg[i].bit_generator.advance(i * 2**64)
References
Seeding and State¶

Seed the generator 
Get or set the PRNG state 
Parallel generation¶

Advance the underlying RNG asif delta draws have occurred. 

Not implemented. 

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

ctypes interface 
Testing¶

Return randoms as generated by the underlying BitGenerator 