object

fast_random(Algorithm)

  • Algorithm - Random number generator algorithm. One of as183, splitmix64, xoshiro128pp, xoshiro128ss, xoshiro256pp, xoshiro256ss, well512a.

Fast portable random number generator predicates.

Availability:
logtalk_load(random(loader))
Author: Paulo Moura
Version: 3:0:0
Date: 2026-02-23
Compilation flags:
static, context_switching_calls
Implements:
public pseudo_random_protocol
public sampling_protocol
Uses:
list
Remarks:

  • Single random number generator: This object provides a faster version of the random library object but does not support being extended to define multiple random number generators.

  • Randomness: Loading this object always initializes the random generator seed to the same value, thus providing a pseudo random number generator. The randomize/1 predicate can be used to initialize the seed with a random value.

  • as183: Algorithm AS 183 from Applied Statistics. 32-bit PRNG with period 2^60. Not cryptographically secure.

  • xoshiro128pp: Xoshiro128++ random number generator. 32-bit state-of-the-art PRNG with period 2^128-1. Algorithm by David Blackman and Sebastiano Vigna.

  • xoshiro128ss: Xoshiro128** random number generator. 32-bit PRNG with period 2^128-1. Algorithm by David Blackman and Sebastiano Vigna.

  • xoshiro256pp: Xoshiro256++ random number generator. 64-bit state-of-the-art PRNG with period 2^256-1. Algorithm by David Blackman and Sebastiano Vigna.

  • xoshiro256ss: Xoshiro256** random number generator. 64-bit PRNG with period 2^256-1. Algorithm by David Blackman and Sebastiano Vigna.

  • splitmix64: SplitMix64 random number generator. 64-bit PRNG primarily used for seeding other generators. Algorithm by Guy L. Steele Jr. et al.

  • well512a: WELL512a 16x32-bit state-of-the-art PRNG with period 2^512-1. Algorithm by by François Panneton, Pierre L’Ecuyer, and Makoto Matsumoto.

  • Algorithms backend compatibility: The SplitMix64, Xoshiro256++, and Xoshiro256** algorithms require support for unbound integer arithmetic.

Inherited public predicates:
 bernoulli/2  beta/3  between/3  binomial/3  chi_squared/2  circular_uniform_cartesian/3  circular_uniform_polar/3  dirichlet/2  enumerate/2  exponential/2  fisher/3  gamma/3  geometric/2  get_seed/1  gumbel/3  hypergeometric/4  logistic/3  lognormal/3  logseries/2  maybe/0  maybe/1  maybe/2  maybe_call/1  maybe_call/2  member/2  normal/3  permutation/2  poisson/2  power/2  random/1  random/3  randseq/4  randset/4  select/3  select/4  sequence/4  set/4  set_seed/1  standard_cauchy/3  standard_exponential/1  standard_gamma/2  standard_normal/1  standard_t/2  swap/2  swap_consecutive/2  triangular/4  uniform/1  uniform/3  von_mises/3  wald/3  weibull/3

Public predicates

reset_seed/0

Resets the random generator seed to its default value. Use get_seed/1 and set_seed/1 instead if you need reproducibility.

Compilation flags:
static, synchronized
Mode and number of proofs:
reset_seed - one

randomize/1

Randomizes the random generator using a positive integer to compute a new seed. Use of a large integer is recommended. In alternative, when using a small integer argument, discard the first dozen random values.

Compilation flags:
static, synchronized
Template:
randomize(Seed)
Mode and number of proofs:
randomize(+positive_integer) - one

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

seed_/2

Stores the current random generator seed values (a ground but otherwise opaque term).

Compilation flags:
dynamic
Template:
seed_(Algorithm,Seed)
Mode and number of proofs:
seed_(+atom,-ground) - one

Operators

(none)

See also

fast_random, random(Algorithm), random, backend_random