Setting random seed

[Guest YetAnotherUsername]

I don't see any functions in the documentation for setting the random seed, and a few old requests in these forums.

How do I set the random seed? I need a sequence of random numbers, but need a seed as well so I can replay the exact same sequence on another machine. I intend passing the seed as a command line parameter.

Thanks.

[Valuater]

I don't see any functions in the documentation for setting the random seed, and a few old requests in these forums.

How do I set the random seed?  I need a sequence of random numbers, but need a seed as well so I can replay the exact same sequence on another machine.  I intend passing the seed as a command line parameter.

Thanks.

<{POST_SNAPBACK}>

not sure... might work for ya..i was just just playing with the idea 8)

#include <GuiConstants.au3>

Dim $random_[8], $pass_on; comma delimited

For $x = 1 To 6
    $random_[$x] = Random(1, 50, 1)
Next    
$pass_on = $random_[1] & "," & $random_[2] & "," & $random_[3] & "," & $random_[4] & "," & $random_[5] & "," & $random_[6]

msgbox(0,"random numbers = " & $x -1 & " ","The winning lotto numbers are  " & $pass_on & "  ")

8)

[/dev/null]

I don't see any functions in the documentation for setting the random seed, and a few old requests in these forums.

How do I set the random seed?  I need a sequence of random numbers, but need a

You can't, as the seed is set internally with the current time (according to source 3.1.0).

Cheers

Kurt

[hgeras]

I'm not sure exactly what a random seed is....Maybe what I'll say sound stupid. If I got this right ,you want fixed patterns of random numbers but in any computer ran....

If that is right,then the only thing you could do to ensure this is to make some txt files with let's say 4000 random numbers each (if im not wrong it will be around 8KB including @CR) and fileinstall() them in your script... Now instead of calling Random() you will read from the file for random numbers but always in the same pattern....

If I got this right ,appraise me.Otherwise ignore me....

[jdickens]

That works.

Or just put an algorithm that makes the random numbers in your script and pass the seed, so to speak. Calculate pi for example.

J

[Ster]

i was curious about a rand_seed also. i'm disappointed there is no seed generator.

in anycase, for those who didnt know, a random seed is usually based on the current timestamp.

also the reason you want a random seed generator is so that you DO NOT have a reproducable random number pattern.

[hgeras]

I need a sequence of random numbers, but need a seed as well so I can replay the exact same sequence on another machine

That's what i saw and brought up the idea...

Any way now i got it better... in a few words you need a random seed to either not have a reproducable pattern or have one at will,right? Correct me if i'm wrong...

[jdickens]

Usually you want a truly random value when the application is deployed, but frequently you want reproducible random numbers during development, for proper debugging.

J

[Jef]

I've also searched for a method to seed the random() function. Unfortunately AutoIt does not provide a way to seed the generator. And that's a real pitty, because random() uses the best random number generator currently available (the Mersenne Twister). A solution is the program your own Random Number Generator.

For people wanting to know more about random number generators, I recommend reading an article I've written for "Basically Speaking" (I think it was in 1997 or 98).

The generator I propose is the L'Equyer LCG3 generator. It's one of the best around (read my article what is meant with "the best"), and is suitable even for high-demanding scientific work. And yes, it can be seeded.

Here is the AutoIt code:

$seed1 = 1234

$seed2 = 2345

$seed3 = 3456

For $i = 1 To 5

$RN = Rand($seed1, $seed2, $Seed3)

MsgBox(0, "Rand", "Random number "&$i&"= " &$RN)

Next

Exit

Func Rand(ByRef $seed1, ByRef $seed2, ByRef $seed3)

; Composite Pseudo Random Number Generator

; Source: Pierre L'Ecuyer, Communications of the ACM, 31, 6, June 88

; An excellent Pseudo RNG with an extremely long period ( >8*10^12).

;

; Returns: single precision uniformly distributed random number

; from range 0.0 ..... 1.0

; Input: Seed1% Seed value generator 1. Value: 1..32362 (inclusive)

; Seed2% Seed value generator 2. Value: 1..31726 (inclusive)

; Seed3% Seed value generator 3. Value: 1..31656 (inclusive)

Local $itemp, $icombined

;*** First algorithm

$itemp = Int($seed1/206)

$seed1 = 157 * ($seed1 - $itemp*206) - $itemp*21

If $seed1 < 0 Then $seed1 = $seed1 + 32363

;*** Second algorithm

$itemp = Int($seed2/217)

$seed2 = 146 * ($seed2 - $itemp*217) - $itemp*45

If $seed2 < 0 Then $seed2 = $seed2 + 31727

;*** Third algorithm

$itemp = Int($seed3/222)

$seed3 = 142 * ($seed3 - $itemp*222) - $itemp*133

If $seed3 <0 Then $seed3 = $seed3 + 31657

;*** Combine the algorithms

$icombined = $seed1 - $seed2

If $icombined > 706 Then $icombined = $icombined - 32362

$icombined = $icombined + $seed3

If $icombined < 1 Then $icombined = $icombined + 32362

;*** Scale to (0.0 , 1.0]

Return $icombined * 3.0899E-5

EndFunc