Message: Re: Random generator correlation on quad-core PC Not Logged In (login)
 Next-in-Thread Next-in-Thread
 Next-in-Forum Next-in-Forum

None Re: Random generator correlation on quad-core PC 

Forum: Run Management
Re: Question Random generator correlation on quad-core PC (Ilya)
Date: 08 Jun, 2007
From: Vladimir IVANTCHENKO <>

On Fri, 8 Jun 2007, Ilya wrote:

> *** Discussion title: Run Management
> Email replies to must include:
>   In-Reply-To: <"/runmanage/189">
>   Subject: ...change this to be about your reply.
> Dear all,
> I have encountered a problem for which I don't see immediate solution. I
> am running 4 instances of one simulation program on a quad-core PC.
> These simulations use each different random seed numbers that are
> restored from different files in the beginning of run (similar as in
> /examples/novice/N03). I am using the defaul random generator.
> Normally if I run the simulations on different PC's I get perfectly
> uncorrelated outputs. But after looking at the results obtained in 4
> simulations on quad-core PC I found that the outputs are almost
> identical (only few events out of 3e6 are different).
> I start the simulations within about 1 min time interval.
> Can somebody explain why this happens (I guess it is due to some
> correlation of random generators but why...?)? And how to avoid this
> correlation?
> I am using GEANT4.8.2.p1 under SUSE Linux
> Thanks a lot for help, Ilya.


If you use saving of random numbers per event and restore random numbers 
from file you share the same file for all processes. In that case you need 
run 4 applications from different subdirectories.


Inline Depth:
 1 1
 All All
Outline Depth:
 1 1
 2 2
 All All
Add message: (add)

 Add Message Add Message
to: "Re: Random generator correlation on quad-core PC"

 Subscribe Subscribe

This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews

[ Geant 4 Home | Geant 4 HyperNews | Search | Request New Forum | Feedback ]