Random number generator

### 7.25 Random number generator

- `set_seed/1`, `randomize/0`
- `get_seed/1`
- `random/1`
- `random/3`

#### 7.25.1 `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.

#### 7.25.2 `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.

#### 7.25.3 `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 |  | `type_error(variable, Number)`

Portability

GNU Prolog predicate.

#### 7.25.4 `random/3`

Templates

  `random(+number, +number, -number)`

Description

`random(Base, Max, Number)` unifies `Number` with a random number such that `Base` ≤ `Number` < `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 |  | `type_error(variable, Number)`

Portability

GNU Prolog predicate.

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