Re: [ROOT] Can I fit a gaussian on to a ntuple plot... how?

From: Siva Subramania (siva@uhhep.phys.uh.edu)
Date: Fri Apr 12 2002 - 20:57:33 MEST


Dear Rene,
I used the same thing before giving the mail also, actually, when I 
use ntuple.Fit("gaus","area"); I am getting a table of values of the 
mean, sigma, error, step size, first derivative, and so on.  But 
nothing is plotted on the graph ie over the ntuple. I also have given 
ntuple.SetOptFit(1111), still, nothing is displayed about the 
probability, Chi2 and others on the Legend.  So what to do now? I 
tried a lot of things, but couldn't figure out. Still trying. Can you 
do me a favor, try to give a solution based on the the TNtuple Example 
script or the TTree Example given in the documentation. You have 
plotted an ntuple graph, plotting the age distribution in the same 
chapter on Trees, try to tell me, how would you now fit a gaussian 
distribution to the age distribution shown. Please.... reply.
Thanx,
Yours,
Shiva.

On Thu, 11 Apr 2002, Rene Brun wrote:

> Hi Shiva,
> 
> See TTree::Fit
> 
> example:
>    ntuple.Fit("gaus","px")
> 
> Rene Brun
> 
> On Thu, 11 Apr 2002, Siva Subramania wrote:
> 
> > Hi,
> > I am new to using ntuples, I managed to understand about ntuples, and I 
> > think, they are nearly the same as histograms, so if I can fit a gaussian 
> > on to a histogram, I should be able to - on an ntuple also, but
> > I am having trouble with fitting a gaussian function on to a ntuple plot. 
> > Can I do it or not? If I can, then how to?  Please reply.
> > Thanx,
> > Yours,
> > Shiva.
> > 
> 
> 



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