Re: [ROOT] TH2 histograms and correlation factor.

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Aug 26 2003 - 15:13:13 MEST


Hi Sara,

see an example in tutorial "fit2d.C"

Rene Brun

On Tue, 26 Aug 2003, Sara VECCHIO 
wrote:

> Hi rooters!
> Here's a (maybe stupid) question from a quite new user.
> 
> I have a TH2 histogram scatter plot, in which points follows quite well an 
> exponential line. I need to check this hypotesis and to get the time 
> constant. 
> Using TH1::fit doesn't 
> work as I would (if I defined a TF2 "y-[0]*exp(x/[1])" all the pad is 
> filled with black points!). 
> I've also tried to use TH2::GetCorrelationFactor(1,2) with a log scale 
> along y axis. But I'm not sure of what this function really does (ROOT 
> reference guide is sometimes too cryptic for me...), and it also look 
> insensitive to the log scale.
> I vaguely know that things should be easier with TProfile histograms, but 
> I don't know how to convert a TH2F in a TProfile.
> 
> Could someone help me?
> 
> Thanks in advance,
> Sara
> 



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