Class: RandomGNUSmalltalk

• Inheritance
• Description
• Instance protocol
  • accessing-reading
  • private
  • reading
• Examples

Inheritance:

   Object
   |
   +--Stream
      |
      +--Random
         |
         +--RandomGNUSmalltalk

Package:

stx:libbasic2

Category:

Magnitude-Numbers-Random

Version:

rev: 1.4 date: 2021/01/20 12:15:50

user: cg

file: RandomGNUSmalltalk.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
=======================================================================================
DO NOT USE THIS GENERATOR FOR CRYPTOGRAPHY OR OTHER SECURITY RELATED WORK, 
because linear congruential generators are predictable and can be broken easily!

Smalltalk/X includes a better generator named RandomGenerator, 
which uses the best available generator of the system 
(either OS-random, /dev/random or as a less dangerous fallback, an RC4-based random generator).
Please use that one.
=======================================================================================

A simple random numbers - thanks to Steves GNU Smalltalk

This implements a linear congruential maximum period random number generator
which passes the spectral test for randomness for dimensions 2 3 4 5 6.

Notice: although being included here,
        this file is NOT covered by the ST/X license, but by
        the FSF copyLeft (see copyright method).

        You can redistribute it under the terms stated there ...
        Also, the price you pay for ST/X does not include a charge for
        this file - it has to be considered as a separate piece of
        software, which can be copied and given away without any 
        restriction from my (CG) side.

copyright
======================================================================
|
| Copyright (C) 1988, 1989 Free Software Foundation, Inc.
| Written by Steve Byrne.
|
| This file is part of GNU Smalltalk.
|
| GNU Smalltalk is free software; you can redistribute it and/or modify it
| under the terms of the GNU General Public License as published by the Free
| Software Foundation; either version 1, or (at your option) any later version.
| 
| GNU Smalltalk is distributed in the hope that it will be useful, but WITHOUT
| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
| FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
| details.
| 
| You should have received a copy of the GNU General Public License along with
| GNU Smalltalk; see the file LICENSE.  If not, write to the Free Software
| Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  
|
======================================================================

see notice in (Random>>documentation)

Instance protocol:

 maxInteger

 nextBoolean

return true or false by random

Usage example(s):

|r| r := Random new. Transcript showCR:r nextBoolean. Transcript showCR:r nextBoolean. Transcript showCR:r nextBoolean. Transcript showCR:r nextBoolean.

Usage example(s):

|r bag| r := Random new. bag := Bag new. 1000000 timesRepeat:[ bag add:(r nextBoolean). ]. Transcript showCR:bag contents

 nextInteger

return the next integral random number,
in the range 0 .. modulus (which is less than 16r3FFFFFFF).
From Sedgewick's 'Algorithms', based on Lehmer's method.

Take care, this returns an even number after each odd number!

Usage example(s):

|r| r := Random new. Transcript showCR:r nextInteger. Transcript showCR:r nextInteger. Transcript showCR:r nextInteger. Transcript showCR:r nextInteger.

 setSeed: seedValue

set the initial seed and intialite the PRNG parameters.
These numbers implement a maximum period generator which passes
the spectral test for randomness for dimensions 2 3 4 5 6 and
the product does not overflow 2 raisedTo:29.

These numbers are carefully choosen, so don't change them,
unless you know what you are doing!

 step

compute the next random integer

 next

return the next random number in the range ]0..1[

Usage example(s):

|r| r := Random new. Transcript showCR:r next. Transcript showCR:r next. Transcript showCR:r next. Transcript showCR:r next.

Examples:

    |rnd|

    rnd := RandomGNUSmalltalk new.
    10 timesRepeat:[
        Transcript showCR:(rnd next)
    ]

    |rnd|

    rnd := RandomGNUSmalltalk new.
    10 timesRepeat:[
        Transcript showCR:(rnd nextIntegerBetween:1 and:6)
    ]