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Forum: Run Management
Re: Question How much is the standard deviation in RandPoisson? (Cejo George)
Date: 13 Mar, 2013
From: Marc Verderi <Marc Verderi>

Hello,

     If you are using a Poisson distribution of mean m, you have no 
freedom for its variance, which is m also, hence its standard deviation 
is sqrt(m). For such a high mean value you are using (60000.) you have 
mostly no difference between a Poisson distribution and a Gaussian one 
of mean m and again standard deviation sqrt(m). Of course, for the 
Gaussian case you can choose both the mean and standard deviation 
independently.
     Are you suspecting any problem with RandPoisson which triggered 
your question ?

Cheers,
Marc

On 03/13/2013 10:04 AM, Cejo George wrote:
> *** Discussion title: Run Management
>
> Dear all,
>   I have the included the following  code in my program
>   CLHEP::RanecuEngine theRanecuEngine;
>   double m=60000;
>   long num=CLHEP::RandPoisson::Shoot (&theRanecuEngine,m);
>
> I wish to know what is the default standard deviation used here.
>
> With Thanks and Regards, Cejo George
>
> -------------------------------------------------------------
> Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at:
> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/runmanage/340.html

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