object

random

Portable random number generator predicates. Core predicates originally written by Richard O’Keefe. Based on algorithm AS 183 from Applied Statistics.

Availability:

logtalk_load(random(loader))

Author: Paulo Moura

Version: 2:11:0

Date: 2023-11-24

Compilation flags:

static, context_switching_calls

Implements:

public pseudo_random_protocol

Uses:

list

Remarks:

• Multiple random number generators: To define multiple random number generators, simply extend this object. The derived objects must send to self the reset_seed/0 message.

• 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.

Inherited public predicates:

 between/3  enumerate/2  get_seed/1  maybe/0  maybe/1  maybe/2  maybe_call/1  maybe_call/2  member/2  permutation/2  random/1  random/3  randseq/4  randset/4  select/3  select/4  sequence/4  set/4  set_seed/1  swap/2  swap_consecutive/2

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

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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

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Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

seed_/3

Stores the current random generator seed values.

Compilation flags:

dynamic

Template:

seed_(S0,S1,S2)

Mode and number of proofs:

seed_(-integer,-integer,-integer) - one

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Operators

(none)

See also

fast_random, backend_random