Random Number Generator - Gaussian Distribution

[andybiochem]

Hi,

Here's a quick math function to generate random numbers based on the normal distribution (gaussian distribution).

This is the Box-Muller polar transformation FYI

#include <Array.au3>
#include <File.au3>

$Mean = 150
$StandardDeviation = 10.0

Dim $GaussianData[501]

For $i = 1 to (UBound($GaussianData) - 1)
    $GaussianData[$i] = _Random_Gaussian($Mean,$StandardDeviation,5)
Next

_ArrayDisplay($GaussianData)

Func _Random_Gaussian($nMean,$nSD,$iDP = 3)
;******************************************
; Box-Muller polar transform gaussian RND
;******************************************
; $iMean = The mean of the distribution
; $iSD = desired standard deviation
; $iDP = data precision (d.p.)
    Do
        $nX = ((2 * Random()) - 1)
        $nY = ((2 * Random()) - 1)
        $nR = ($nX^2) + ($nY^2)
    Until $nR < 1
    $nGaus = ($nX * (Sqrt((-2 * (Log($nR) / $nR)))))
    Return StringFormat("%." & $iDP & "f",($nGaus * $nSD) + $nMean)
EndFunc

By the way, how is Random() seeded in AutoIT? Is it standard time-based?...is there going to be a problem here with calling Random() in quick succession?

Edited August 4, 2008 by andybiochem

[Nutster]

Hi,

Here's a quick math function to generate random numbers based on the normal distribution (gaussian distribution).

By the way, how is Random() seeded in AutoIT? Is it standard time-based?...is there going to be a problem here with calling Random() in quick succession?

AutoIt uses a special random number feature (read the included docs for more details) and initializes the random function at the beginning of an AutoIt session using the current time. To experiment, create a compiled script that just outputs the current time (in detail) and a random number to a Notepad session. Call this compiled script 10 times in a row and see what the output looks like.

[DMEE]

Just curious on how to obtain "true" random numbers.

Does anyone have an idea: if one substracts two reals of kind=4 from each other to be placed in a kind=8 variable. How random is the number that is obtained?

[join]

i got a REALLY good script for random, check out http://www.autoitscript.com/forum/index.ph...=random+numbers

easy + good = BEST