[gate-users] uncorrelated random number seeds

Dirk Kruecker d.kruecker at fz-juelich.de
Mon Oct 17 10:36:46 CEST 2005

Dear Hiroshi

the method  Mutanga Theodore described does not create independent random 
seeds but in most cases this should not be a real problem.  Maybe there is 
some other reason for your results but it is difficult to say what the reason 
is for the correlations you see. I posted a detailed explaination how to 
handle the random files on this list at Jun 30, 2005. I also include a set of 
random seed files that are indepent for sure. 

Best regards

Am Montag, 17. Oktober 2005 09:01 schrieb Hiroshi Watabe:
> Dear Gate-users,
> I try to do 4 simulations with different seeds. In the past gate-users
> talk, I found the article (posted by Mutanga Theodore on 17 Dec 2004)
> which explain how to generate different seeds files.
> As the article explains, I did mock simulation with 10 Bq source and
> generated four different endOfRun.rndm. By using the command
> /random/resetEngineFrom, I initialized random seeds.
> I supposed to get four different results but four simulations produced
> very similar results. I say "similar" because I got exactly same
> projection data but the root outputs were slightly different in each
> others. In the root file, I found only event ID and time
> were different but else (for instance, source position and global
> position) were exactly same in Singles trees (I'm doing SPECT simulation).
> Any suggestions and advice are appreciate.
> Hiroshi
> --------------------------------------------------
>              Hiroshi Watabe, PhD
> watabe at ri.ncvc.go.jp
> Department of Investigative Radiology
> Advanced Medical Engineering Center
> National Cardiovascular Center Research Institute
> 5-7-1 Fujishirodai, Suita, Osaka 565-8565
> Tel:06-6833-5012-2560 or 06-6833-5004-2560
> Fax:06-6835-5429
> --------------------------------------------------
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