Re: FWHM calculation

From: Marc Escalier <escalier_at_lal.in2p3.fr>
Date: Wed, 21 Jul 2010 10:38:10 +0200

Hi,

for your example, you could do :

htemp->Fit("gaus")

for the FWHM :
http://en.wikipedia.org/wiki/Full_width_at_half_maximum

from the fit, you will obtain the sigma, if you wish the FHWM from the gauss, you just take : 2.35482 * sigma
if you wish to compute the FHWM from the histogram, then you would search for the maximum :
myhisto->GetMaximumBin()
then make a loop on the bins to the left up to have myhisto->GetBinContent() is below the maximum make a loop on the bins to the right of the bin of the maximum to have myhisto->GetBinContent() is below the maximum

then you have the bin left, the bin right, you deduce the central values of these bins
with something like myhisto->GetBinCenter(TheBinYouWish)

good luck

---

Farzaneh a écrit :
>
> Dear root users,
>
> I’m new root users and try to use root for analyzing GATE data. I have
> installed root 5_14 on both Ubuntu and Redhat5.
>
> I want to fit a Gaussian distribution on attached histogram, and
> calculate FWHM. Can anyone help me?
>
> Thanks in advance.
>
> Farzaneh Adibpour
>
> MSc Student, Department of Medical physics and Biomedical Engineering,
>
> Tehran University of Medical Sciences,
>
> Member of Medical Imaging Systems Research Group, Research Center for
> Science and Technology in Medicine
>
> Email: adibpour_at_razi.tums.ac.ir
>
> f.adibpour_at_gmail.com
>
> Cell:+989123679749
>
>
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Received on Wed Jul 21 2010 - 10:43:45 CEST