"======================================================================

|

| 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.  

|

 ======================================================================"

"

|     Change Log

| ============================================================================

| Author       Date       Change 

| claus      10 Jan 94    added more comments, added 'contents'

| claus       5 Apr 90    brought into Smalltalk/X

| sbyrne     19 Sep 89    Converted to use real method categories.

| sbyrne      3 Jul 89    created.

|

"

Stream subclass:#Random

       instanceVariableNames:'seed'

       classVariableNames:''

       poolDictionaries:''

       category:'Magnitude-Numbers'

!

Random comment:'

Copyright (C) 1988, 1989 Free Software Foundation, Inc.

Written by Steve Byrne.

'!

!Random class methodsFor: 'documentation'!

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)

"

!

version

"

"

!

documentation

"

    random numbers - thanks to Steves GNU Smalltalk

    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.

"

! !

!Random class methodsFor: 'instance creation'!

new

    "return a new random generator"

    ^self basicNew setSeed

! !

!Random methodsFor:'testing'!

chiSquare

    "perform a chiSquare-test on the receiver"

    "returns on Sun3 93.40000000000009"

    ^self chiSquare: 1000 range: 100

    "Random new chiSquare"

!

chiSquare: n range: r

    | f t s |

    s := 1234567.

    f := Array new: r + 1.

    1 to: r + 1 do: [ :i | f at: i put: 0 ].

    n timesRepeat:

        [ s := (seed * 31415821) + 1 bitAnd: 16r3FFFFFFF.

          t := s \\ r.

          f at: t + 1 put: (f at: t + 1) + 1 ].

    t := 0.

    1 to: r do: [ :i | t := t + (f at: i) squared ].

    ^r asFloat * t / n - n

!

atEnd

    "instances of random can always give more numbers"

    ^false

! !

!Random methodsFor: 'blocked methods'!

contents

    "blocked from use - contents makes no sense for random generators"

    self shouldNotImplement

!

nextPut: value

    "blocked from use - it makes no sense for randoms"

    self shouldNotImplement

! !

!Random methodsFor: 'accessing-reading'!

nextInteger

    "return the next integral random number,

     in the range 0 .. 16r3FFFFFFF.

     From Sedgewick's 'Algorithms', based on Lehmer's method"

    "the times: is a kludge - times does not convert to LargeInteger on overflow"

    seed := (seed times:31415821) + 1 bitAnd: 16r3FFFFFFF.

    ^ seed

    "|r|

     r := Random new.

     Transcript showCr:r nextInteger.

     Transcript showCr:r nextInteger.

     Transcript showCr:r nextInteger.

     Transcript showCr:r nextInteger.

    "

!

next

    "return the next random number in the range 0..1"

    seed := (seed times:31415821) + 1 bitAnd: 16r3FFFFFFF.

    ^ self nextInteger / 16r3FFFFFFF asFloat

    "|r|

     r := Random new.

     Transcript showCr:r next.

     Transcript showCr:r next.

     Transcript showCr:r next.

     Transcript showCr:r next.

    "

!

nextBoolean

    "return true or false by random"

    "thanks to Peter Deutsch ..."

    seed := (seed times:31415821) + 1 bitAnd: 16r3FFFFFFF.

    ^ seed < 16r20000000

    "|r|

     r := Random new.

     Transcript showCr:r nextBoolean.

     Transcript showCr:r nextBoolean.

     Transcript showCr:r nextBoolean.

     Transcript showCr:r nextBoolean.

    "

!

nextBetween:start and:stop

    "return a random between start and stop.

     claus: the original GNU version has a bug in returning values

     from the interval [start .. stop+1]"

    |rnd|

    rnd := self next.

    rnd := rnd * (stop asFloat - start asFloat + 1.0).

    rnd := rnd + start asFloat.

    ^ rnd

    "|r|

     r := Random new.

     Transcript showCr:(r nextBetween:1 and:10).

     Transcript showCr:(r nextBetween:1 and:10).

     Transcript showCr:(r nextBetween:1 and:10).

     Transcript showCr:(r nextBetween:1 and:10).

    "

!

nextIntegerBetween:start and:stop

    "return an integral random between start and stop"

    |rnd|

    rnd := self next.

    rnd := rnd * (stop asFloat - start asFloat + 1.0).

    ^ (rnd + start) truncated.

    "|r|

     r := Random new.

     Transcript showCr:(r nextIntegerBetween:1 and:10).

     Transcript showCr:(r nextIntegerBetween:1 and:10).

     Transcript showCr:(r nextIntegerBetween:1 and:10).

     Transcript showCr:(r nextIntegerBetween:1 and:10).

    "

!

nextMatchFor: aNumber

    "generate the next random, return true iff it has the same

     value as aNumber. Redefined to avoid endless reading."

    ^self next = aNumber

! !

!Random methodsFor: 'private'!

setSeed

    "set the initial seed value based on the current time"

    seed := Time secondClock bitAnd: 16r3FFFFFFF

! !