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8.25  Random number generator

8.25.1  set_seed/1, randomize/0

Templates

set_seed(+integer)
randomize

Description

set_seed(Seed) reinitializes the random number generator seed with Seed.

randomize reinitializes the random number generator. This predicates calls set_seed/1 with a random value depending on the absolute time.

Errors

Seed is a variable  instantiation_error
Seed is neither a variable nor an integer  type_error(integer, Seed)
Seed is an integer < 0  domain_error(not_less_than_zero, Seed)

Portability

GNU Prolog predicates.

8.25.2  get_seed/1

Templates

get_seed(?integer)

Description

get_seed(Seed) unifies Seed with the current random number generator seed.

Errors

Seed is neither a variable nor an integer  type_error(integer, Seed)
Seed is an integer < 0  domain_error(not_less_than_zero, Seed)

Portability

GNU Prolog predicate.

8.25.3  random/1

Templates

random(-float)

Description

random(Number) unifies Number with a random floating point number such that 0.0 ≤ Number < 1.0.

Errors

Number is not a variable  uninstantiation_error(Number)

Portability

GNU Prolog predicate.

8.25.4  random/3

Templates

random(+number, +number, -number)

Description

random(Base, Max, Number) unifies Number with a random number such that BaseNumber < Max. If both Base and Max are integers Number will be an integer, otherwise Number will be a floating point number.

Errors

Base is a variable  instantiation_error
Base is neither a variable nor a number  type_error(number, Base)
Max is a variable  instantiation_error
Max is neither a variable nor a number  type_error(number, Max)
Number is not a variable  uninstantiation_error(Number)

Portability

GNU Prolog predicate.


Copyright (C) 1999-2013 Daniel Diaz Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved. More about the copyright
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