# [ROOT] Statistical error of the Integral of a Gaussian

Date: Sat Feb 28 2004 - 03:15:55 MET

Dear Rooters,

I am new to the list, and I have the following which I coud not figure out
how to do it under root. I'm fitting my J/psi peaks by a Gaussian function :
f=N*Exp[-(x-\bar{x})^2/2 sigma^2]. Then I utilized the function
Integral(min,max) to find the area or the number of counts under this fit.
.
.
.
n[j]->Fit("Gaus","R");
G->SetParameters(par[0],par[1],par[2]);
float mean = par[1];
float sigma = par[2];
float mlo = mean-3.0*sigma;
float mhi = mean+3.0*sigma;
cout <<mean<<" and "<<sigma<<" and " <<mlo<<"and "<<mhi<<endl;
float binw = n[j]->GetBinWidth(1);
double COUNTS = G->Integral(mlo,mhi)/binw;
.
.
.

I need to know how to find the statistical error of the integral, i.e. "COUNTS"
in root.

Thank you very much

Ahmed.

=====
"EAST OR WEST, HOME IS BEST".

Ahmed Al-Jamel
Physics Department(http://www.physics.nmsu.edu)
New Mexico State University
Box 30001, MSC 3D
Las Cruces, NM 88003-8001
Tel (off): (505)-646-7614.
http://www.feynman.nmsu.edu
http://www.phenix.bnl.gov/phenix/WWW/publish/ahmed1/

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