[ Arithmetic | Reference Manual | Alphabetic Index ]

seed(+Seed)

Sets the initial seed Seed for generating random numbers with random/1 or frandom/1.
Seed
Integer.

Description

Used to initialise the seed which is used for the generation of random numbers by random/1 or frandom/1. Setting the same seed value with seed/1 enables the generation of a repeatable random sequence with random/1 ie. pseudo-random number generation.

The seed value should be an integer in the range 1 .. 2^31-1.

Modes and Determinism

Exceptions

(4) instantiation fault
Seed is not instantiated.
(5) type error
Seed is instantiated, but not to an integer.

Examples

Success:
      ?- repeat, random(S).
      S = 464880439   More? (;)
      S = 285401533   More? (;)
      yes.

      ?- seed(1), repeat, random(S).
      S = 2078917053   More? (;)
      S = 143302914   More? (;)
      yes.
      ?- seed(1), repeat, random(S).
      S = 2078917053   More? (;)
      S = 143302914   More? (;)
      yes.

See Also

random / 1