Random numbers

Author(s): Daniel Cabeza.

This module provides predicates for generating pseudo-random numbers

Usage and interface

Library usage:
:- use_module(library(random)).
Exports:
- Predicates:
  random/1, random/3, srandom/1.

Documentation on exports

PREDICATErandom/1

random(Number)

Number is a (pseudo-) random number in the range [0.0,1.0]

Usage:

The following properties should hold at call time:
(term_typing:var/1)Number is a free variable.
The following properties hold upon exit:
(term_typing:float/1)Number is currently instantiated to a float.
The following properties hold globally:
(foreign_interface_properties:foreign_low/2)The Prolog predicate PrologName is implemented using the function ForeignName. The same considerations as above example are to be applied.

PREDICATErandom/3

random(Low,Up,Number)

Number is a (pseudo-) random number in the range [Low, Up]

Usage 1:

If Low and Up are integers, Number is an integer.

The following properties should hold at call time:
(basic_props:int/1)Low is an integer.
(basic_props:int/1)Up is an integer.
(term_typing:var/1)Number is a free variable.
The following properties hold upon exit:
(basic_props:int/1)Number is an integer.
The following properties hold globally:
(foreign_interface_properties:foreign_low/2)The Prolog predicate PrologName is implemented using the function ForeignName. The same considerations as above example are to be applied.

Usage 2:

The following properties should hold at call time:
(basic_props:flt/1)Low is a float.
(basic_props:num/1)Up is a number.
(term_typing:var/1)Number is a free variable.
The following properties hold upon exit:
(basic_props:flt/1)Number is a float.

Usage 3:

The following properties should hold at call time:
(basic_props:int/1)Low is an integer.
(basic_props:flt/1)Up is a float.
(term_typing:var/1)Number is a free variable.
The following properties hold upon exit:
(basic_props:flt/1)Number is a float.

PREDICATEsrandom/1

srandom(Seed)

Changes the sequence of pseudo-random numbers according to Seed. The starting sequence of numbers generated can be duplicated by calling the predicate with Seed unbound (the sequence depends on the OS).

Usage:

Calls should, and exit will be compatible with:
(basic_props:int/1)Seed is an integer.
The following properties hold upon exit:
(basic_props:int/1)Seed is an integer.
The following properties hold globally:
(foreign_interface_properties:foreign_low/2)The Prolog predicate PrologName is implemented using the function ForeignName. The same considerations as above example are to be applied.

Documentation on imports

This module has the following direct dependencies:

System library modules:
foreign_interface_properties.
Packages:
prelude, initial, condcomp, assertions, assertions/assertions_basic, isomodes, foreign_interface, basicmodes, regtypes, engine(foreign_types).